The lines are forming a triangle, because the shape formed has 3 sides making it up. The sum of the measures of the interior angles of a triangle is equal to 180 degrees, so that means all the angles (x, y, and z) will add up to 180 in an equation.
Make angles x, y, and z add up to 180 in an equation. Substitute the given values for x and y, 90 and 53, into the equation and solve for the value of angle z (variable z).
x + y + z = 180
(90) + (53) + z = 180
Combine like terms (add 90 and 53 together).
143 + z = 180
Subtract 143 from both sides of the equation to solve for the measure of angle z.
z = 37°
