Since a square has a complementary angle, it’s four angle in total is 360 degrees. But the angle b is given in the question and says what angle it was. So, angle b is 4x+10. What do we do about these numbers? We just created them into an equation and solve them algebraically. The way to solve it is this way:
4(4x+10) = 360
16x +40 = 360
16x= 320
X= 20
The answer is x= 20
