Question

It took Fran 1.8 hours to drive to her​ mother's house on Saturday morning. On her return trip on Sunday ​night, traffic was​ heavier, so the trip took her 2 hours. Her average speed on Sunday was 6 mph slower than on Saturday. What was her average speed on Sunday​?

Answer 1

Answer:

  54 mph

Step-by-step explanation:

Let s represent the slower speed. The product of speed and time is distance, which did not change between the two trips. So, we have ...

  1.8(s +6) = 2(s)

  10.8 = 0.2s . . . . eliminate parentheses, subtract 1.8s

  54 = s . . . . . . . . divide by 0.2

Fran's average speed on Sunday was 54 miles per hour.

____

Her trip was 108 miles long.