The 2nd bus will catch up to the 1st bus after 2 hours.
For this problem, the value t will be the time since the 2nd bus started traveling. So let's create a couple of expressions to indicate the distance each bus travels at time t
First bus is traveling at 40 mph and has a 1 hour head start, so it has a 40 mile lead. The distance traveled at t time is
40t + 40
The second bus is traveling at 60 mph, so its equation is
60t
Now let's set the two equations equal to each other and solve for t
40t + 40 = 60t
40 = 20t
2 = t
So the 2nd bus will catch up to the 1st bus after traveling for 2 hours.
