Peter leaves Riverdale at 10:00 a.m. and starts pedaling his bicycle at 10 mph. If John starts on the same path at 2:00 p.m., when will he catch Peter if he pedals at 15 mph?

10t = 15(t â€“ 4)

t=12 hours --> which is the correct answer

But why is that when i use the alternative scenario where

Peter = t+4 (instead of t)

John = t (instead of t-4)

we have the equation 10(t+4) = 15t

t = 8 hours --> which is wrong

shouldn't the two methods yield the same answer?

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Impossible is nothing