Ben spends 20% of his after-tax income on his car. If his car payment is $400 and he pays 1/3 of his gross income in taxes, how much does he make per month before taxes?
Let's think: First divide that amount of the car payment by 20% to find Ben's after - tax salary: $400 / .2 = $2000. Then find the proportion of his salary Ben keeps after taxes by subtracting the tax rate from 1: 1 - 1 / 3 = 2 / 3. Then divide Ben's after - tax salary by the proportion of his salary he keeps to find his before - tax salary: $2000 / 2 / 3 = $3000.. The answer is: 3000.

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?
Let's think: 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.

Rose bought a plant with a 10% discount. If the price is $10, how much did Rose pay after the discount?
Let's think: The plant has $10 x 10 / 100 = $1 discount. So, Rose paid $10 - $1 = $9 for the plant.. The answer is: 9.

A dental office gives away 2 toothbrushes to every patient who visits. His 8 hour days are packed and each visit takes .5 hours. How many toothbrushes does he give in a 5 day work week?
Let's think:
Each day he does 8 / .5 = 16 visits. So he does 16 * 5 = 80 visits a week. That means he gives away 80 * 2 = 160 toothbrushes a week.. The answer is: 160.