Answer: x = 3
=======================================
Work Shown:
12% = 12/100 = 0.12
x + 12% of x = x + 0.12x = 1.12x = 3.36
1.12x = 3.36
x = 3.36/1.12
x = 3
---------------
Check:
12% of 3 = 0.12*3 = 0.36
x + 12% of x = 3 + 12% of 3 = 3 + 0.36 = 3.36
Or you could say 1.12x = 1.12*3 = 3.36
The answer is confirmed.