Question

If the speed of a car is decreased by 12 km/h, it takes 1 hour more to cover a
distance of 240 km. Find the original speed of the car.​

Answer 1

Answer:

Step-by-step explanation:

Let the speed of the car be x km per hour

Distance = 240 km

Speed of car = x km per hour

Time = Distance/speed

Time = 240/x

If the speed of the car is decreased by 8 km per hour, it takes 1 hour more to cover a distance of 240 km

Time during changed speed

= 240 km /x - 8 km per hour

240/(x - 8) - 240/x = 1 hour

240x —240 (x - 8)/ x (x - 8) = 1 hour

240x — 240x + 1920/ x^2 - 8x = 1 hour

1920/x^2 - 8x = 1 hour

Cross multiplication

x^2 - 8x = 1920

x^2 - 8x -1920 = 0

x^2 - 48x + 40 x - 1920

x (x - 48) + 40 (x - 48)

(x + 40) (x - 48)

x = —40 is not possible being negative hence discarded

x = 48 km per hour

The original speed of the car was 48 km per hour