Question

Points A and B are 70 km apart on a highway. A car starts from A and another car starts from B simultaneously. If they travel in the same direction, they meet in 7 hours. But, if they travel towards each other, they meet in 1 hour. Find the speed of each car.

Answer 1

:Let the distance between A & B is 70km.

Car-1 & Car-2 both travel in the same direction.

But their speed is not the same. So they both meet in 7 hours.

Let the speed of Car-1 be x and Car-2 be y.

If they travel towards each other they meet in 1 hour.

when they are moving in the same direction, the speed is x-y.

when they are moving towards each other, the speed is x+y.

Distance = 70km

We know, $Speed=\frac{Distance}{Time}$

So, Distance = Speed $\times$ Time

7(x-y)=70

x-y=10---›(i)

similarly

1(x+y)=70

x+y=70---›(ii)

Solving (i) & (ii)

x+y=70
x -y=10
_____
2x=80.

x = $\frac{80}{2}$=40 Km/ hr.

substitute x in x+y=70

so,40+y=70;

y=30 km/hr.

The speed ofCar-1 is 40km/hr.

The speed of Car-2 is 30 km/hr.