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.
