Question

For a particular 5 hours journey, Alex travelled at an average speed of (2x + 5) km/h for

the first 2 hours. He then travelled at an average speed of (3x - 5) km/h for the last 3
hours to complete his journey.

(a) Write down an expression, in terms of x, to represent the distance travelled by
Alex in the first 2 hours of his journey
​

Answer 1

4x + 10

Explanation:

Given

Let

`t = time`

`s = speed`

So:

`t = 2; s = (2x +5)` --- first 2 hours

`t = 3; s = (3x -5)` --- last 3 hours

Required

Distance covered in the first 2 hours

Distance (d) is calculated as:

`Distance = speed * time`

i.e.

`d = s * t`

For the first 2 hours, we have:

`t = 2; s = (2x +5)`

So:

`d = (2x + 5) * 2`

Open bracket

`d =2x * 2 + 5 * 2`

`d =4x + 10`

Hence, the distance covered in 4x + 10