Question 206567
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Craig Drives 20 miles per hour faster than sara. 
in the same time that sara drives 225 miles, craig drives 325 miles. find the speed of each car
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        The answer in the post by @HyperBrain is INCORRECT due to arithmetic error on the way.

        I came to provide a correct solution



d=vt so t=d/v
Let x be the Sara's speed, in miles per hour.
Then the Craig's speed is (x+20) miles per hour.
225/x=325/(x+20)
Multiply both sides by x(x+20)
225(x+20)=325x
225x+4500=325x
100x=4500
x = 45 mi/hr ((Sara' speed)
x+20 = 45 + 20 = 65 mi/hr (Craig' speed).


<U>CHECK the travel time</U>.  &nbsp;&nbsp;{{{225/45}}} = 5 hours.  &nbsp;&nbsp;{{{325/65}}} = 5 hours.     &nbsp;&nbsp;&nbsp;&nbsp;Precisely correct !


Solved correctly.