Speed of two trains

Question

Suppose two trains leave a city at the same time, traveling in opposite directions. One train travels 4 mph faster than the other. In 4 hours, the trains are 360 miles apart. Find the speed of each train.

Answer 1

Let x and y be the speed of each train.

y = x+4

distance = rate × time

4x + 4y = 360

4x + 4(x+4) = 360

8x +16 = 360

8x = 344

x = 43

y = 47

The speed of the trains is 43 mph and 47 mph.

Answer 2

360 = 4(T + T+4) = 4(2T+4) = 8T =16

8T = 360-16 = 344

T = 344/8 = 43 mph

T+4 = 47 mph