Balance the equation

Question

12 - 6 = 9 -

Answer 1

You can think of 12 as "9 + 3" which turns the problem into:

(9 + 3) - 6 = 9 - ___

Now, apply the associative property to re-group:

9 + (3 - 6) = 9 - ___

Now combine 3 - 6 to get -3:

9 + (-3) = 9 - ___

9 - 3 = 9 - ___

so obviously the blank is " 3"

12 - 6 = 9 - 3