Each tree A gives her six good oranges a month 10 x .6 = 6. Each tree B gives her five good oranges a month because 15 x (1 / 3) = 5. On average, a tree gives her 5.5 oranges a month because .5(6) + .5(5) = 5.5. She has ten total trees because 55 / 5.5 = 10.
The answer: 10
Reverse engineering the question: Salaria is growing oranges this summer. She bought two types of trees. She has 50% of tree A and 50% of tree B. Tree A gives her 10 oranges a month and 60% are good. Tree B gives her 15 oranges and 1/3 are good. If she gets 55 good oranges per month, how many total trees does she have?

First find the total increase in Bob's earnings: $0.50 / hour * 40 hours / week = $20 / week. Then find the weekly decrease in Bob's housing assistance: $60 / month / 4 weeks / month = $15 / week. Then subtract the lost assistance from the increased wages to find Bob's net increase in money: $20 / week - $15 / week = $5 / week.
The answer: 5
Reverse engineering the question: Bob gets rent assistance because he's low-income. If he gets a raise of $0.50/hour and works 40 hours a week, how much more will he actually earn a week if his housing benefit is reduced by $60/month?

Charles drew 6 + 6 = 12 pictures. He has 20 - 12 = 8 papers left. So Charles drew when he came back from work 8 - 2 = 6 pictures.
The answer: 6
Reverse engineering the question: Charles bought 20 papers to draw. Today Charles drew 6 pictures. Yesterday he drew 6 pictures before going to work and some pictures when he came back. How many pictures did Charles draw when he came back from work knowing that he has 2 papers left?

After half an hour, the number of balloons that had blown up is 1 / 5 * 200 = 40. The number of balloons that haven't blown up so far is 200 - 40 = 160. In the next hour, 2 * 40 = 80 balloons blow up. The number of balloons that haven't blown up now is 160 - 80 = 80.
The answer: 80
Reverse engineering the question:
A hot air balloon with 200 balloons is blowing up. After about half an hour, 1/5 of the total number of balloons in the hot air balloon have blown up. After another hour, twice the number of balloons that had already blown up also blow up. How many balloons in the hot air balloon remain intact?