When does the jam start?

想象一个有两辆车的道路,每个长度 $L$. Car 1 gets on the road at $t = 0$moving at $v_{1}$, and car 2 gets on the road at $t =_{2}$, moving at $v_{2} > v_{1}$.

At what time does the front of car 2 to get in contact with the back of car 1?

Solve for the case where

$v_{1} = 20\text{ m/s}, v_{2} = 25 \text{ m/s}, t_{2} = 100 \text{ s}$, and $L = 5 \text{ m}$.

Express your answer in seconds.