Question

Train A has a speed 20 miles per hour greater than that of train B. If train A travels 270 miles in the same times train B travels 210 miles, what are the speeds of the two trains?

Answer 1

speed of train A = 70 + 20 = 90 miles per hour

speed of train B = 70 miles per hour

Explanation:

Let

speed of train B = a

speed of train A = a + 20

Recall

speed = distance/time

The travel time is same for both train. Therefore, let us make time subject of the formula in the speed equation.

Time = distance/speed

270/a + 20 = 210/a

cross multiply

270a = 210(a + 20)

270a = 210a + 4200

270a - 210a = 4200

60a = 4200

divide both sides by 60

a = 4200/60

a = 70

speed of train A = 70 + 20 = 90 miles per hour

speed of train B = 70 miles per hour