By the triangle sum theorem, the sum of the angles in a triangle is equal to 180°. Therefore, Using the
(32) + 90° + (x + 10) = 180°. To solve for x, first combine like terms to get 4x + 100 =
180. Using the subtraction property of equality, 4x = 80. Then, using the
x = 20. To find the measure of angle A, use the
substitution property to get m angle A = 3(20). Finally, simplifying the expression gets
mZA= 60°