An angle measures 12 degrees less than 3 times its supplement

Given that the angle measures 12 degrees less than 3 times the supplement, the size of the angle will be:
suppose the size of the supplement is x;
the size of the angle supplementary to x will be:
 3x-12
Given that the sum of supplementary angles is 180, thus;
x+(3x-12)=180
solving for x we get:
4x-12=180
4x=180+12
4x=192
x=192/4
x=48
the size of the supplementary angles will be:
48*3-12
=132