Question

Two trains leave the station at the same time, one heading east and the other west. The eastbound train travels 20 miles per hour slower than the westbound train. If the two trains are 800 miles apart after 4 hours, what is the rate of the eastbound train?

Answer 1

90 mph

Explanation:

Let the speed of the westbound train (A) be x mph; and

the speed of the eastbound (B) train be (x-20) mph.

We know that distance = speed x time

so distance traveled by A = 4x; and

the distance traveled by B = 4 (x - 20) = 4x - 80.

Adding these distances up to get:

4x + (4x - 80) = 800

4x + 4x = 800 - 80

8x = 720

x = 720/8

x = 90

Therefore, the rate at which the eastbound train travels is 90 mph.

Answer 2

Let x be the speed of eastbound train

The eastbound train travels 20 miles per hour slower than the westbound train.

so the speed of westbound train is x + 20

Distance = speed * time

Time = 4 hours

Distance traveled by each bound train = 4x

Distance traveled by westbound train = 4(x+20)

Two trains are 800 miles apart

4x + 4(x+20) = 800

4x + 4x + 80 = 800

8x + 80 = 800

Subtract 80 from both sides

8x = 720

Divide both sides by 8

x = 90

The speed of east bound train is 90 miles per hour