Q: Mr. Dubois buys a new car for $13,380. He pays $5,400 and pays the rest by giving $420 a month. In how many months will the car be fully paid for?
A: Dubois has to pay $13,380 – $5,400 = $7,980 more. He will pay that in $7,980 : $420 = 19 months. The answer is 19.

Q: William's class set a goal each week of the number of cans of food that is to be collected. On the first day, 20 cans were collected. Then the number of cans increased by 5 each day. If they collected 5 days a week to reach their goal, how many cans of food was their goal per week?
A: On the second day, they collected 20 + 5 = 25 cans. On the third day, they collected 25 + 5 = 30 cans. On the fourth day, they collected 30 + 5 = 35 cans. On the fifth day, they collected 35 + 5 = 40 cans. Thus, the goal of William's class is to collect a total of 20 + 25 + 30 + 35 + 40 = 150 cans of food per week. The answer is 150.

Q: Quinten sees three buildings downtown and decides to estimate their heights. He knows from a book on local buildings that the one in the middle is 100 feet tall. The one on the left looks like it is 80% of the height of the middle one. The one on the right looks 20 feet shorter than if the building on the left and middle were stacked on top of each other. How tall does Quinten estimate their total height to be?
A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
He estimates the building on the left is 80 feet tall because 100 x .8 = 80. The combined height of the left and middle is 180 because 100 + 80 = 180. The building on the right he estimates as 160 feet because 180 - 20 = 160. He estimates the combined height as 340 feet because 80 + 100 + 160 = 340. The answer is 340.