Posted by Marie on Monday, August 29, 2011 at 5:10pm.
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?

math  Mgraph, Monday, August 29, 2011 at 6:26pm
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.
Then
S/40*(t+8)=S/30*t
30t+240=40t