A and B are alternate exterior angles, so they are congruent to each other
this means the equations will be equal to each other
5x+20 = 3x+60
-20 -20
5x = 3x+ 40
-3x -3x
2x= 40
2x/2= 40/2
x= 20
the answer is x=20
then check your work:
5 (20) + 20= 120
3 (20) + 60= 120
they are equal to each other so the answer 20 is correct