At 1:00 p.m., a car leaves a city and travels north at 
a rate of 55 mi/h. An hour later, a second car leaves
the city and travels south at a rate of 60 mi/hr. At 
what time will the two cars be 285 miles apart?

Let the time when they meet be t hours after 1:00 p.m., 
which is the total time the first car traveled.

 FIRST        SECOND         THEIR
 CAR'S    +   CAR'S    =   DISTANCE
DISTANCE     DISTANCE        APART

We use DISTANCE = RATE × TIME

The first car's RATE is 55 and its TIME is t hours, so
its distance is 55t

The second car's RATE is 60 and its TIME is 1 hour less
than the first car's, or t-1. So its distance is 60(t-1)


 FIRST        SECOND         THEIR
 CAR'S    +   CAR'S    =   DISTANCE
DISTANCE     DISTANCE        APART

  55t     +  60(t - 1) =      285

Solve that and get t = 3 hours after 1:00 p.m., or 4:00 p.m.

Edwin