Question

How fast must a car travel to overtake a bus in 5 hours, if the bus is averaging 30 kilometers per hour and left 3 hours before the car?​

Answer 1

The car must move 48 km/h.

Explanation

• Denote x km/h the speed of the car.

5*x km while the bus for 5 hours travel the distance:

5*30=150 km ,since the bus left 3 hours before the car its total distance from the car is 150+3*30=240 km. The car overtake the bus when 5*x=240 where x=48 km/h.

Answer 2

Let the speed of the car be
`x` km/h

Car travel to overtake a bus in 5 hours =
`5*x` km

The bus for 5 hours travel the distance:

`\longrightarrow 5*30=150` km

Where the bus left 3 hours before the car its total distance from the car is :

`\longrightarrow 150+3*30=240` km

The car overtake the bus when
`5*x=240`

`\Longrightarrow\sf{5*x= 240 }`

`\Longrightarrow\sf{x = \frac{ \cancel{240}}{\cancel{5}} }`

`\Longrightarrow\sf{x = \red{48} }`

Answer: The car must move 48 km/h.