Q: Charles is jogging while listening to his favorite album. He runs at 6 MPH when he's got music on and 4 MPH when he doesn't. His album is 40 minutes long. How many minutes will it take him to jog 6 miles?
A: He runs at .1 miles per minute because 6 / 60 = .1. While the album is playing he can run 4 miles because 40 x .1 = 4. He has to run 2 miles without the album because 6 - 4 = 2. Without music he runs 1 / 15 miles per minute because 4 / 60 = 1 / 15. He will run the remaining 2 miles in 30 minutes because 2 / (1 / 15) = 30. It will take him 70 minutes in total because 40 + 30 = 70. The answer is 70.

Q: In a rice field, you can get a total of 20 sacks of rice every harvest. If the yield increases by twenty percent after every harvest, what is the total number of sacks of rice you can get after the first and second harvest?
A: There were 20 x 0.20 = 4 sacks of rice increase after the first harvest. So the total sack of rice that you can get on the next harvest 20 + 4 = 24. Therefore the total number of sacks of rice you will get on the first and second harvest is 20 + 24 = 44. The answer is 44.

Q: John's camera broke so he decided to rent one for 4 weeks. It was a $5000 camera and the rental fee was 10% of the value per week. His friend who was there when it broke agreed to pay 40% of the rental fee. How much did John pay?
A:
The rental fee is 5000 * .1 = $500 per week. So it cost 500 * 4 = $2000. His friend pays 2000 * .4 = $800. So he pays 2000 - 800 = $1200. The answer is 1200.