Let's say the number is x.
The equation will be:
1/3x + 12 = x
(one third of a number + 12 equals to the number)
Solving the equation:
subtract 1/3x from both sides:
12 = 2/3x
divide by 2
6 = 1/3x
multiply with 3
18 = x
Your number is 18, its one-third is 6, which is 12 less than the number itself.
