SOLUTION: Wilfred and Wendy have a long distance bike race. Wilfred rides at 20 km/h and has a 2 hour head start. Wendy travels at 28 km/h. How long does it take for Wendy to catch up to Wil

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Question 1111031: Wilfred and Wendy have a long distance bike race. Wilfred rides at 20 km/h and has a 2 hour head start. Wendy travels at 28 km/h. How long does it take for Wendy to catch up to Wilfred? Use distance = speed × time.
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
d, distance upon catching-up
d%2F20-d%2F28=2

highlight%28d=140%29


Time to catch up, 140%2F28=highlight%285%29, hours

Answer by ikleyn(52817) About Me  (Show Source):
You can put this solution on YOUR website!
.
One line solution: 

How long does it take for Wendy to catch up to Wilfred = %282%2A20%29%2F%2828-20%29 = 40%2F8 = 5 hours.

Explanation: 

Wilfred is 2*20 = 40 km ahead (head start).   It is the initial distance.  And it is the NUMERATOR of my formula.


Their relative speed is 28-20 = 8 km/h   meaning that the distance between them decreases at the rate of 8 km/h.

                                                                           And it is the DENOMINATOR of my formula.


It gives the time to catch up  40%2F8 = 5 hours.

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