Question 1132385
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<pre>

Let x be the speed of Jack.


Then the distance Jack traveled during 2 hours was  2x.


Jill traveled 80 miles more, so she traveled  (2x+80) miles.


Her speed was (x+10) miles per hour.

She spent 3.5 hours, hence


    3.5*(x+10) = 2x + 80.


Solve the equation


    3.5x + 35 = 2x + 80

    3.5x - 2x = 80 - 35

    1.5x = 45

    x = {{{45/1.5}}} = 30 miles per hour was the Jack' speed.     <U>ANSWER</U>
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Solved.