SOLUTION: A boy riding a bicycle at the rate of 10 miles per hour and a car traveling 40 miles per hour are traveling in the same direction on the same road. If the car passes a road sign 3

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Question 708515: A boy riding a bicycle at the rate of 10 miles per hour and a car traveling 40 miles per hour are traveling in the same direction on the same road. If the car passes a road sign 30 minutes after the bicycler does, in how many minutes will the car overtake the bicycler?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Tough to think about this one. I see this pathway so far:

How far back was the car (40 miles per hour) when the bicyclist reached the road sign? We do not yet need the bicyclist's speed or distance - not yet - but we CAN determine how far back was the car. 40 miles per hour Multiplied by 1/2 hour (which is the 30 minutes) equals 20 miles back.

Now imagine we have a number line to represent the road. At zero is the road sign. NEGATIVE 20 is where the car is when the bicycle is at zero.
At time equals zero, car is at -20, bicycle is at 0 on the line.
some time t passes. At some particular t, car has gone %28-20%29%2B40%2At, and bicycler has gone 0%2B10%2At. We want these positions on the line to be equal; so my thought is now,
%28-20%29%2B40t=0%2B10t, find t.