Aman has an old truck that gets 15 miles per gallon. in january, he started using his bike to commute to and from work. he lives 9.8 miles away from his job site. gasoline during the month averaged $3.75 a gallon. how much money did he save on gasoline if he rode his bike to and from work 18 times instead of driving?

To begin, you need to find the overall mileage he would have traveled. You can find this by taking 36 (the amount of total trips made) and multiplying it by 9.8 miles.

36 x 9.8 = 352.8

Divide 352.8 by the 15 miles per gallon, giving you 23.52 gallons. 

Finally, multiply the gallons by the price ($3.75) and you will find your answer, which is $88.20.