If I drive x mph for t hours and then y mph for 2t hours wha

If I drive x mph for t hours and then y mph for 2t hours, what is the expression for average speed?

Solution

average speed = (total distance)/(total time)
distance = rate*time
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Partial distance: xt miles
Partial distance: y*2t miles
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Total time = t + 2t
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Equation:
Average speed = (xt+2yt)/3t = (x+2y)/3 mph