Question

A freight train and a passenger train leave a rail yard at the same time and travel on parallel tracks,

The passenger train travels 5 mph faster than the freight train. The combined distance traveled
after 3 hours is 135 miles. What is the average speed of the freight train?

A 70 mph
B 20 mph
C 22 mph
D 19 mph

Answer 1

C. 22 mph

Explanation

Assign the speed of the freight train as; x mph

Since the passenger train travels 6 mph faster than the freight train, its speed will be; (x + 6) mph

In 2 hours, the freight and passenger trains will have traveled (distance = speed * time);

2x and 2(x + 6) miles respectively

Both add up to 100 miles. Therefore;

2x + 2(x +6) = 100

4x + 12 = 100

4x = 88

x = 22

x + 6 = 28