2007 Pascal Problem 22

Asafa ran at a speed of 21 km/h from P to Q to R to S, as shown. Florence ran at a constant speed from P directly to R and then to S. They left P at the same time and arrived at S at the same time. How many minutes after Florence did Asafa arrive at point R?

\textbf{(A)}\ 0\quad \textbf{(B)}\ 8\quad \textbf{(C)}\ 6\quad \textbf{(D)}\ 7\quad \textbf{(E)}\ 5

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Full credit to this problem is given to the CEMC, you may view all Pascal contests here.