SOLUTION: (I have tried the box method, inputting all this data into an equation, and it boils down to me thinking that there is no solution!) Riva's father drives to work each morning at

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Question 553281: (I have tried the box method, inputting all this data into an equation, and it boils down to me thinking that there is no solution!)
Riva's father drives to work each morning at an average rate of 50 mi/h. Coming home the traffic is heavier, and he averages only 40 mi/h. His place of work is 20 miles from where Riva's family lives. What is the father's average rate of speed for the daily round trip?
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
If he travels 20 miles at 50 mi/h, then time = D/r = 20/50 = .4 hr .

If he travels 20 miles at 40 mi/hr, then time = D/r= 20/40 = .5 hr .

The AVERAGE SPEED = (TOTAL DISTANCE)/(TOTAL TIME) = 40 miles/.9 hr = 44.44 mi/hr.

I think maybe your box method may not be appropriate for this one!