Question 1119567
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<pre>
Let x be the slower speed in kilometers per hour.

Then the faster speed is (x+3) km/h.


The time equation is 


{{{36/x}}} + {{{36/(x+3)}}} = 7.    ( <<<---=== each fraction in the left side is the time, spent to cover 36 kilometers 
                                with the corresponding speed).


To solve it, multiply both sides by x*(x+3); then simplify and solve the quadratic equation.


<U>Answer</U>.  The slower speed is 9 km/h; the faster speed is 12 km/h.


<U>Check</U>.   {{{36/9}}} + {{{36/12}}} = 4 + 3 = 7 hours.
</pre>

Solved.