Question 292876
Recall that d = rt.  In this case, the distances are the same, so we just need to set the rate * time equal for both busses.

let x = Hours for the first bus to travel.

30x = 50(x-2)
30x = 50x - 100
-20x = -100
{{{highlight(x = 5)}}}

To verify:  The first bus travels 5 hours @ 30 mph:  150 miles.  
The second bus travels 3 hours (5 - 2) @ 50 mph:  150 miles.  OK.