Question

Mary is driving home from work and needs to make two stops. She first drives at a rate of 25 mph to the supermarket, which is 175 miles way from her work, and then she drives to her house, which is 80 miles away from the supermarket, at a rate of 40 mph. What was Mary's average speed for the entire trip?

Answer 1

175 divide by 25 should be 7
then using 80 divide by 40 is 2
7+2=9
then 2 times 40, and 7 times 25, the result is 285
285 divide by 9 get 31.6666......... or 31.7