Opposite angles of a rectangle add up to 180 degrees, and each angle of a rectangle is 90 degrees.
Make angle Q and angle S add up to 180 in an equation, and make angle Q = 90 degrees.
90 + (7x + 55) = 180
Combine like terms (90 + 55).
145 + 7x = 180
Subtract 145 from both sides.
7x = 35
Divide both sides by 7.
x = 5
B) 5 is your answer.
