Question

How do you find four consecutive multiples of 5 whose sum is 90?

Answer 1

`15,20,25,30`

Explanation:

We know that the multiples' will add up to 90, so their average must be `90/4`, or `22.5`. Since there are an even number of multiples (4), none of them will touch the average, but they will be centered around it. Therefore, the multiples must be `15,20,25,30`
Check:
`15+20+25+30=90`

Answer 2

`15`, `20`, `25` and `30`

Explanation:

Let the smallest number of the bunch be `x`,

`x+(x+5)+(x+5+5)+(x+5+5+5)=90`

Simplify,

`4x+30=90`

Subtract `30` from both sides,

`4x=60`

Divide,

`x=15`

Since the smallest number is `15`, the rest are as follows: `20`, `25` and `30`.

Answer 3

The multiples are `" "15," "20," "25," "30`

Explanation:

Any multiple of `5` can be written as `5x`

The next multiple will be when `x` increases by `1`

The sum of four consecutive multiples of `5` is `90`

`5x +5(x+1)+5(x+2)+5(x+3)=90`

`5x +5x+5+5x+10+5x+15 = 90`

`20x +30 =90`

`20x = 60`

`x =3`

So the first multiple of `5` is `5xx3=15`

The multiples are `" "15," "20," "25," "30`