Question

How do you solve `9n+18=81`?

Answer 1

`color(green)(n=7)`

Explanation:

Given
`color(white)("XXX")9n+18=81`

Noticing that all the terms are multiples of `9`
we can simplify this by dividing both sides by `9`
`color(white)("XXX")n+2=9`

Now if we subtract `2` from both sides, we get
`color(white)("XXX")n=7`