Answer:
Step-by-step explanation:
All square angles are 90° exactly 90° so we can use that to your advantage. since "7x + 3" is one of the square's angles, that means 7x + 3 must equal 90°. (7x + 3)° = 90°.
7x + 3 = 90
7x = 90 - 3
7x = 87
7x/7 = 87/7
x = 87/7
