Liz sold her car at 80% of what she originally paid. She uses the proceeds of that sale and needs only $4,000 to buy herself a new $30,000 car. How much cheaper is her new car versus what she originally paid for her old one?
Let's think: If Liz needs only $4,000 to buy a new $30,000 car, that means she has $30,000 - $4,000 = $26,000 from the proceeds of selling her old car. If she sold her car at 80% of what she originally paid for and sold it for $26,000 then she originally paid $26,000 / 80% = $32,500 for her old car. If she paid $32,500 for her old car and the new one is $30,000 then, the new one is $32,500 - $30,000 = $2,500 cheaper.. The answer is: 2500.

In the fall, 20,000 high school students apply to Harvard University for college. In the spring, 5% of those 20,000 students are accepted to the university. Of the students who are accepted, 90% choose to attend the university, and the other 10% choose to go to other schools. How many students choose to attend Harvard University?
Let's think: The number of students accepted to the university is 20,000 * 0.05 = 1,000 students. The number of students who choose to attend the university is 1,000 * 0.9 = 900 students.. The answer is: 900.

Ali and Sara ate 80 small apples combined. Ali ate 4 times more apples than Sara. How many apples did Sara eat?
Let's think: Let A be the number of apples Ali ate and S be the number of apples Sara ate. We have: A + S = 80 apples. And: A = 4S. Which means: 4S + S = 80. So: 5S = 80. So the number of apples Sara ate is: S = 80 / 5 = 16 apples.. The answer is: 16.

Tony has a terrible toothache and decides to buy some painkillers from the store. He picks up a bottle of 50 pills and takes them home. He takes 2 pills each day three times a day for the first 2 days, before cutting this amount in half for the next 3 days. On the sixth day, he takes a final 2 pills in the morning and ends up feeling better. How many pills are left in the bottle?
Let's think:
Tony starts with 50 pills and takes 2 pills each 3 times a day, meaning he takes 2 * 3 = 6 pills in total. Tony repeats this process for two days in total, meaning over those two days he takes 2 * 6 = 12 pills. Tony then cuts down his pill usage in half, meaning he's now taking 6 / 2 = 3 pills a day. Since he repeats this process for three days, that means he takes 3 * 3 = 9 pills for that period. Adding in the two pills Tony took on the final day, that means he took 12 + 9 + 2 = 23 pills. Since there were 50 pills in the bottle to begin with, this means Tony has 50 - 23 = 27 pills remaining.. The answer is: 27.