Question 933158
Let 3hrs = the duration of the vehicles traveled
    x+15 = the car's speed
      x  = the bus's speed
    300mi= total distance covered

A bus and car travel in opposite directions. After 3 hours, they were 300miles apart. The car is traveling 15mph faster than the bus.
Distance = (rate)(time)

(x+15)(3)+ (x)3 = 300
     3x+45 + 3x = 300
             6x = 255
              x = 42.5

Substitute x with 42.5
42.5+15 = 57.5

The car's speed is 57.5mph while the bus's speed is 42.5mph.

Check
3 (57.5) + 3 (42.5) = 300
      172.5 + 127.5 = 300
                300 = 300