Answer:
6
Step-by-step explanation:
instead of adding, we can use subtraction as our inverse operation
30 - 12 = 18.
to check, we can add 12 and 18 and see what we get.
12+ 18 = 30
Therefor, we are left with 18, but the equation is 3x + 12 = 30. not x + 12 = 30...
so, do 18 divided by 3 and you get 6!
6 = x
