Question: The math teacher would be happy if the class average test score was at least 85. There are 10 students in the class, 5 of which scored a 92 on the test and 4 of which scored an 80. What would the last student have to score to at least make the teacher happy?
Answer with step-by-step thinking: 5 students scored a combined total of 92 * 5 = 460. 4 additional students scored a combined total of 80 * 4 = 320. 9 students therefore scored a combined total of 460 + 320 = 780. We know the total combined score for 10 students must be at least 85 average * 10 students = 850. Therefore, the last student must score at least an 850 - 780 = 70.
So the answer is 70.

Question: Baez has 25 marbles. She loses 20% of them one day. Then a friend sees her and gives her double the amount that Baez has after she lost them. How many marbles does Baez end up with?
Answer with step-by-step thinking: She loses 5 marbles because 25 x .2 = 5. She has 20 marbles after this because 25 - 5 = 20. Her friend gives her 40 marbles because 20 x 2 = 40. Adding those marbles to the 20 she had before, she ends up with 40 marbles + 20 marbles = 60 marbles.
So the answer is 60.

Question: Jenn is saving up money to buy a bike. She has 5 jars full of quarters. Each jar can hold 160 quarters. If the bike costs 180 dollars, how much money will she have left over after buying it?
Answer with step-by-step thinking:
Jenn has 5 * 160 = 800 quarters. The quarters are worth 800 * 0.25 = 200 dollars. After buying the bike she will have 200 - 180 = 20 dollars left.
So the answer is 20.