Prom

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It's time for the annual prom. Nova is on the prom committee with her friends Mei, Ali, Brandon and Rolo. They made all of the decorations and are finally prepared. Nova hopes Brandon, whom she has a crush on, will ask her to go to the prom.
The prom is both something to look forward to and a source of worry. Lloyd complains to his stepsister Tess that he has no date, but Tess recommends to ask anybody, it does not matter who. Mei discovered by now that she has been accepted at a different university than her boyfriend Justin, and worries about telling him as prom approaches. Lucas has been in love with his lab partner Simone, and turns to his friend Corey to help him ask her to the prom. The only one who does not care about the prom is Jesse Richter. He plays truant, rides his motorcycle across the schoolyard, and behaves as if it nothing matters. Principal Dunnan tries to talk to him but does not get through to him.
Meanwhile, Jordan finds an earring in the car of her boyfriend, Tyler but he assures her that he's not cheating. He shows how much he cares for her by taking her on a romantic date inside of the shed with the prom decorations, and asking her to the prom. Unfortunately, they forget to blow out a candle after their departure and it sets the shed and the decorations ablaze. With only three weeks left, Nova is forced to make all new props, but her friends are too busy with other things and can not help her. The principle gives Jesse a choice, either he helps Nova with the decorations, or he can't graduate.
Jesse accepts reluctantly, as does Nova. They realize that they need each other. While Brandon deeply disappoints Nova by not asking her to the prom, she and Jesse grow closer, despite the fact that Jesse finds the idea of prom ridiculous. When Nova discovers that the prom theme of the neighboring school is the same as theirs, Jesse decides to sneak into their school and see how their decorations compare. Unfortunately while trespassing, the security guard notices them and the police catch them after they escape. The police call Nova's parents and when Nova's father arrives he gets extremely mad at Jesse. Nova later apologizes to Jesse and he helps her find a dress. Jesse turns the proverbial "rough diamond with white pit" to be, and also plays truant as much as he needs to fit his little brother and his single mother into his life.
Meanwhile, Lloyd still can not find a date. He gets frustrated and desperate. Lucas asks Simone to a barbecue of his friend Tyler. Tyler tries to talk and flirt with her and she rejects him, because he is dating Jordan. Simone tells Lucas she wouldn't have gone if she had known it was Tyler's party. It seems that Tyler and Simone have a past. Meanwhile, the stress in Mei and Justin's relationship reaches the breaking point, and Mei cancels on Justin for fear of telling him about her acceptance.
At school, Lucas blows off Corey to spend more time with Simone, and asks her to study for the upcoming test with him, to which she agrees. However, as she is about to go to library, Simone is stopped by Tyler, who convinces her to talk with him. He tells her about his feelings for her. Jordan sees the two talking and immediately grasps the situation.
After school, Nova apologizes to Jesse for her dad's behavior. Later, she brings him along as she goes dress shopping, for a second opinion. Back at school, Simone apologizes to Lucas for having ditched him. She has a surprise, tickets to a concert, where Stick Hippo (his and Corey's favorite band) is opening. Lucas wants to take Simone instead of Corey, much to Corey's dismay. Jordan dumps Tyler for his unfaithfulness, and decides to go to prom alone. This prompts him to ask Simone to prom, which is the same night as the concert, and she agrees. Simone tells Lucas that she is sorry, but she cannot go to the concert.
Mei apologizes to Justin for her behaviour and tells him the truth, but instead of feeling hurt that she is going to a different college, he tells her he is proud of her. They agree that they should still go to prom together.
As Lloyd gets rejected by another girl, he spots Lucas sitting outside the school, looking dejected. He learns his situation, and tells Lucas his own mistake with girls and high school. Lloyd tells Lucas that if he really loves Simone, then he should tell her.
Two nights before the prom, Nova, Ali, and Mei are in Nova's room, talking. Nova confesses to them that she has feelings for Jesse, which her dad unfortunately overhears. The next day, Nova's father tells Jesse he cannot ask Nova to prom, because he is "bringing her down". That afternoon, Jesse is unusually hostile towards Nova and deserts her.
On prom night, Lucas climbs a tree to reach Simone's window. He tells her how he feels and begs her not to go to prom, but she goes anyway. Disappointed, Lucas realizes what a bad friend he has been to Corey, and offers him the other concert ticket. The two head off to see their favorite band happily.
At her house, Nova is heartbroken, and refuses to pose for the camera in her prom dress. Her father, worried, explains that he was the one who told Jesse not to ask her to prom. Angered, Nova storms out of the house. Meanwhile, at Lloyd's house, it is revealed that he is taking his sister to prom. At Jesse's house, his mother has a talk with him, and he realizes that he should still take Nova to prom.
At the school, Tyler leads Simone into the building, and almost immediately abandons her. Simone finds out from a couple of girls that it was actually Jordan who dumped Tyler, and Tyler had gone to her with no other option. As Tyler and Jordan are pronounced prom king and queen, Jordan refuses to participate in the king-and-queen dance. When Tyler asks Simone to dance, she refuses and leaves. She goes to the concert parking lot, where she waits for Lucas, and they share a dance.
Nova is having an awful time at prom, and when Ali tells her the fountain centerpiece is broken, she cannot take it any more. As she is about to leave, she hears the fountain start again, and knows the only person who could have fixed it was Jesse. He walks up to her and asks her to prom. She agrees, and they dance followed by a kiss.

Question: How many weeks before prom did the shed burn down?
Answer: Three