Question 1009856
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City A and City B are 200 km apart.  Harry rides his bike 20 km faster than Yoshi rides his bike.  
Find Harry's average speed if he travels from city A to city B in 1 1/7 hour less time than Yoshi.  
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Let u be the Harry' speed, in mph.

Then the Yoshi' speed was u-20.

Time Harry spent for the trip was {{{200/u}}} hours.

Time Yoshi spent for the trip was {{{200/(u-20)}}} hours.

An equation is 

{{{200/(u-20)}}} - {{{200/u}}} = {{{1}}}{{{1/7}}},    or

{{{200/(u-20)}}} - {{{200/u}}} = {{{8/7}}}.

Simplify and solve it for u.

As the first step, multiply both sides by 7u*(u-20).
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