SOLUTION: It took Cathy 1.8 hours to drive to her​ mother's house on Monday morning. On her return trip on Tuesday ​night, traffic was​ heavier, so the trip took her 2 hour

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Question 1070457: It took Cathy 1.8 hours to drive to her​ mother's house on Monday morning. On her return trip on Tuesday ​night, traffic was​ heavier, so the trip took her 2 hours. Her average speed on Tuesday was 7 mph slower than on MondayMonday. What was her average speed on Tuesday​?
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
               SPEED        TIME        DISTANCE
GOING           r            1.8          d
RETURN          r-7          2            d

d is distance both ways, the same for each.
r%2A1.8=%28r-7%29%282%29

1.8r=2r-14
0.2r=14
r=14%2F%280.2%29
highlight%28r=70%29------Monday, going to.
highlight%28r-7=63%29------Tuesday, returning from.