Question 1140833
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20 miles/hour = {{{20/60}}} miles/minute = {{{1/3}}} miles/minute.


Assuming acceleration  "a"  is uniform in time in this case,


     a = {{{delta_v/delta_t}}} = {{{1/3}}} miles/minute : 20 minutes = 1/60 of a mile/minute^2 = {{{60^2/60}}} miles/hour^2 = 60 miles/hour^2.      <U>ANSWER</U>
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