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One driver drives 25 mph faster than another driver does. They start at the same time and after a certain amount of time, one driver has driven 90 miles, and the other driver has driven 165 miles. What are the speeds of the two drivers?

User Richardtz
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1 Answer

4 votes

Answer:

speed of slower driver 30 mph

speed of faster driver = 55 mph

Explanation:

let the speed of slower driver b x mph

given

One driver drives 25 mph faster than another driver does

Speed of faster driver = (x+25) mph

we know time = speed / distance

also in same time faster will travel more distance than the slower one.

thus

driver with speed (x+25) mph would have traveled 165 miles

driver with speed x mph would have traveled 90 miles

time for driver with speed (x+25) mph = 165/(x+25)

time for driver with speed x mph = 90/x

Given that

They start at the same time and after a certain amount of time, one driver has driven 90 miles, and the other driver has driven 165 miles.

\time for driver with speed (x+25) mph =time for driver with speed x mph

165/(x+25) = 90/x

165x = 90(x+25)

=> 165x = 90x + 2250

=> 165x -90x = 2250

=> 75x = 2250

=> x = 2250/75= 30

Thus, speed of slower driver 30 mph

speed of faster driver = 30+25 = 55 mph

User Albert Romkes
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