Ok, so alternate exterior angles are congruent. So 6x+18=x+93 So we want to get x on the side by itself, to do this we would first subtract 18 from both sides. This leaves us with the equation 6x=x+75 We will the subtract a from both sides So the equation is now 5x=75 Well divide both sides by 5 so we can have x completely alone
We are left with the equation x=15
Now to find the measure of angle b, we plug x into the spot So 15+93=108°