SOLUTION: Robert and Brooke are biking along the canal 68 miles apart. They are riding toward each other until they meet. Brooke started 1 hour before Robert, but Robert bikes 4mph faster. I

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Question 793215: Robert and Brooke are biking along the canal 68 miles apart. They are riding toward each other until they meet. Brooke started 1 hour before Robert, but Robert bikes 4mph faster. If they meet 3 hr after Robert starts, find the bike speed of each of them.

I know D=RT
Brooke's distance is x and Roberts is 68-x
Brookes time would be 4 hours since she started an hour earlier and Roberts time would be 3 hours. I'm stuck here.
Answer by josgarithmetic(39630) (Show Source):
You can put this solution on YOUR website!
Let Brooke's speed be r.
Robert's speed is r+4.

Brooke begins travel first and spends h+1 hours until he and Robert meet.
Robert only spends h hours time, because he began travel ONE HOUR AFTER Brooke.
The description of the time involved is confusing; but it seems no variable should be needed for time quantities. They meet in three hours after Robert starts his travel. Robert must have traveled only three hours, and therefore, Brooke, having began 1 hour earlier, traveled for 3+1 hours.

The numeric data is here in tabulated form for you to more clearly understand some of the information:

Bicyclist___________speed___________time_____________distance
Brooke______________r_______________3+1______________r(3+1)
Robert______________r+4_____________3_______________(r+4)3
Total________________________________________________68

Our only unknown variable is r, the speed for Brooke. The obvious distance sum gives us the needed equation:
STEPS:

So Robert's speed is then mph.