<PRE><B>Question 1742</B>
let the speed on Monday be x mph. It takes him 45 minutes (which is 3/4 of an hour), so using speed=distance/time gives:

{{{x=(d/(3/4))}}} or {{{x=(4d)/3}}}. This is equation 1.

On Tuesday, speed is 12mph more, so it is x+12. His time is 9 minutes less, meaning 36 minutes, which is 3/5 of an hour. REMEMBER, the speed is miles per HOUR, so all distances must be miles and all times must be HOURS.

so, its equation is {{{(x+12)=((5d)/3)}}}. This is equation 2.

Equation 1 re-arranges to be {{{3x=4d}}}
Equation 2 re-arranges to be {{{(3x+36)=5d}}}.

We can substitute equation 1 into equation 2 and we get d=36miles.

cheers
Jon.

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