If ABCD is a square, the four angles at the center of the square must be equal, it means that 4 times the given expression for the angle is equal to 360°.
Then, you have:
4(11x + 35) = 360
In order to solve the previous equation for x, you proceed as follow:
4(11x + 35) = 360 apply distribution property
4(11x) + 4(35) = 360
44x + 140 = 360 subtract 140 both sides
44x = 360 - 144
44x = 216 divide by 44 both sides
x = 216/44 simplify the fraction
x = 108/22 = 54/11
Hence, the solution for x is x = 54/11