Since this is a square, its sides must be congruent. This means you can set the given values equal to each other to solve for x.
x + 7 = 4x - 11
Subtract 7 from both sides.
x = 4x - 18
Subtract 4x from both sides.
-3x = -18
Divide both sides by -3.
x = 6
Answer:
x = 6
