Question

The sum of a number and 9 is 12.

Answer 1

x=3

Explanation:

You take 12-9 to get 3 :)

Answer 2

`3`

Explanation:

Simple, all you have to do is backwards equation. If the sum is 12. Subtract 12 by one of the numbers given.

`12 - 9`

`==> 3`

`3 + 9 = 12`