Question

Two cars are 400 miles apart when they start moving towards each other. The speed of the first car is 30 mph. The the second car moves 20 mph faster than the first car. After how many hours will the cars meet?

Answer 1

The number of hours it will take before both cars meet is 5 hours

Explanation:

Here we have, speed of first car, A = 30 mph

Speed of second car, B = (30 + 20) mph = 50 mph

Therefore, we have

Let the point where both cars meet be X and the time before they meet be Y

Then for car A, 30 × Y = X....................(1)

For car B, 50 × Y = 400 - X..................(2)

From plugging the value of X from equation (1) into equation (2) we have;

50·Y = 400 - 30·Y

80·Y = 400

Y = 5 hours

Therefore the number of hours it will take before both cars meet = 5 hours.

Answer 2

t = 5 hrs

Explanation:

let

speed of the first car = 30 mph

speed of the second car = 20 mph + 30 mph = 50 mph

When the cars meet we know both cars will have traveled a total distance of 400 miles.

Therefore,

let's make a distance equation

speed = distance/time

distance = speed × time

first car + second car = 400 miles

30t + 50t = 400

80t = 400

divide both sides b 80

t = 400/80

t = 5 hrs