Q: Vanessa wants to buy a dress she saw at the mall, which costs $80, and she already has $20 in savings. Her parents give her $30 every week, but she also spends $10 each weekend at the arcades. How many weeks will she have to wait until she can gather enough money to buy the dress?
A: Vanessa needs $80 $20 = $60 to buy the dress. She manages to gather $30 - $10 = $20 each week. The number of weeks she has to wait is 60 20 = 3 weeks. The answer is 3.

Q: When Matty was born, the cost of a ticket to Mars was $1,000,000. The cost is halved every 10 years. How much will a ticket cost when Matty is 30?
A: First find the total number of times the cost is halved: 30 years / 10 years / halving = 3 halvings. Then halve the cost once: $1,000,000 / 2 = $500,000. Then halve the cost a second time: $500,000 / 2 = $250,000. Then halve the cost a third time: $250,000 / 2 = $125,000. The answer is 125000.

Q: There is a lot of dust in Susie's house. It takes her 2 hours to vacuum the whole house. She can vacuum each room in 20 minutes. How many rooms does she have in her house?
A:
Susie spends 2 * 60 = 120 minutes vacuuming. Since she can vacuum each room in 20 minutes, she has 120 / 20 = 6 rooms in her house. The answer is 6.