You can
put this solution on YOUR website!The variable that is the same for both of them is time. If I
start my stopwatch when they are 725 mi apart and stop it
when they meet, they have both travelled for the same amount
of time.
Let

= distance that Paul travels

will be the distance that Susan travels
For Paul:

hrs
For Susan:

hrs
Since their times are equal,

Multiply both sides by

Now find

hrs
They will meet in 5 hrs
check:

OK