The stadion

John can run around a circular track in 20 seconds and Eddie in 30 seconds. Two seconds after Eddie starts, John starts from the same place in the opposite direction. When will they meet?

Correct answer:

t =  11.2 s

Step-by-step explanation:

$$\begin{gathered} J=20\text{s} \\ E=30\text{s} \\ {v}_1=s/J \\ {v}_2=s/E \\ s=s_1+s_2 \\ s=v_1\cdot t+v_2\cdot (t+2) \\ s=s/J\cdot t+s/E\cdot (t+2) \\ 1=1/J\cdot t+1/E\cdot (t+2) \\ 1=1/20\cdot t+1/30\cdot (t+2) \\ 5t=56 \\ t=\frac{56}{5}=11.2 \\ t=\frac{56}{5}=11.2=11.2\text{s} \end{gathered}$$

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