Find m∠y if m∠y is six more than three times its supplement

Let x = measure of angle y's supplement
therefore measure y is 3x + 6
if two angles are supplement then they add up to 180
3x+6+x = 180
4x+6 = 180
4x = 174
x= 43.5 <-- thats the angle of angle Y's supplement
angle y is 3(43.5) + 6 = 136.5 degrees