Question

Two cars left the city for a suburb, 480 km away, at the same time. The speed of one of the cars was 20 km/hour greater than the speed of the other, and that is why it arrived at the suburb 2 hour earlier than the other car. Find the speeds of both cars.

Answer 1

Time taken by car A = 6 hr and time taken by car B is 8 hours

Explanation:

Given:

Distance, d = 480 km

Let x be the time taken by B to reach the destination:

So,

Time taken by car A to reach the destination = x -2

We know:

Distance = speed X time

speed = $\frac{distance}{time}$

On substituting the value we get:

Speed of car A = $\frac{480}{x - 2}$

Speed of car B = $\frac{480}{x}$

Since car A travelled 20 km/hr faster than the car B, the equation becomes:

$\frac{480}{x-2} = \frac{480}{x} + 20$

Multiplying both sides by (x - 2) we get:

$480 = \frac{480(x-2)}{x}+ 20(x-2)\\ \\480 = \frac{480x - 960}{x} + 20x - 40\\\\480 = \frac{480x - 960 + 20x^2 - 40x}{x} \\\\480x = 20x^2 + 440x - 960\\\\20x^2 - 40x - 960 = 0\\\\x^2 - 2x - 48 = 0\\\\x = 8$

Therefore, time taken by car A = x - 2

                                                   = 8 - 2 hr

                                                   = 6 hr

Time taken by car B = 8 hr

Answer 2

Answer:

80 km/h and 60 km/h

Step-by-step explanation:

this is the answer lol i did my rsm hw and got it right so idk