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The distance from home to work is 60*(2/3) = 40 miles.
Here the ratio represents 40 minutes, that are of an hour.
The way back takes 75 minutes, or 1 hour and 15 minutes, i.e. hours.
Therefore, the average speed driving back from work to home is = = 8*4 = 32 miles per hour.
ANSWER. The average speed driving back from work to home is 32 miles per hour.
Solved, explained, calculated and completed.
Enjoy (!)
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Ignore the solution by @josgarithmetic, giving you an answer mph. It is TOTALLY WRONG !
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From day to day and from year to year, so called "tutor" @josgarithmetic deceives the visitors of this forum,
giving them wrong solutions.
From day to day, the visitors applaud him, demonstrating total absence of common sense and elementary basic knowledge.
Dear visitors, he will continue deceive you every day, until you applaud him (!)