Question

Cars A and B leave the same place and travel in the same direction along a straight road. Car A travels at 60 km/h and car B travels at 72 km/h. After how long will they be at 8km apart​

Answer 1

`(2)/(3)` hours

Explanation:

Let
`t` be equal to the time that passes for Car A and Car B to be 8 km apart.

Let
`A` be equal to the distance that Car A travels within
`t`.

Let
`B` be equal to the distance that Car B travels within
`t`.

1) Create equations

`Distance = Time*Velocity`

Therefore:

`A=60t`

`B=72t`

We also know that the distance between the two cars would be 8 km. Therefore:

`B-A=8`

2) Solve for t (the time it takes for Car A and Car B to be 8 km apart)

Plug
`A=60t` and
`B=72t` into
`B-A=8`

`72t-60t=8\\12t=8\\t=(8)/(12) \\t=(2)/(3)`

Because the velocity unit is km/h, we know that t will be in hours. Therefore, Car A and Car B were 8 km apart after
`(2)/(3)` hours.

I hope this helps!