Question 1097579
Please help with the following:
Show all work as you solve the following problem and write complete answers, including appropriate units:
 Trevon left school and drove east.  Two hours later Molly left school driving 10 km/h faster in an effort to catch up to him.  After four hours Molly finally caught up.  What was Trevon's average speed?

Thanks! 
<pre>Let Trevon's average speed be S
Then Molly's is: S + 10
When Trevon arrived at the "catch-up point," he'd traveled 6 (2 + 4) hours
When Molly arrived at the "catch-up point," she'd traveled 4 hours
As they'd traveled the same distance when she caught up, we get the following DISTANCE equation: 6S = 4(S + 10)
6S = 4S + 40
6S - 4S = 40
2S = 40
S, or Trevon's average speed = {{{highlight_green(matrix(1,4, 40/2, "=", 20, "km/h"))}}}