posted by Marie on .
My brother and I walk the same route to school every day. My brother takes 40 minutes to get to school and I take 30 minutes. Today, my brother left 8 minutes before I did. How long will it take me to catch up with him?
Let the distance to school S, my speed=S/30
the speed of my brother=S/40 and
I catch up with him after t min.