Mary and Ann are going sledding. Mary slides down a hill that's 630 feet long at a speed of 90 feet/minute. Ann slides down a hill that's 800 feet long at a rate of 40 feet/minute. How much longer does Ann's trip take than Mary?
First find the total time Mary's trip takes: 630 feet / 90 feet/minute = <T>divide(630, 90)=7.0 minutes
Then find the total time Ann's trip takes: 800 feet / 40 feet/minute = <T>divide(800, 40)=20.0 minutes
Then subtract Mary's time from Ann's time to find the difference: 20 minutes - 7 minutes = <T>subtract(20, 7)=13 minutes
