Question

A straight angle is divided into three adjacent angles. The first angle measures 40° , the second measures

(3x + 10)°, and the third measures (2x + 20)°. What is the value of x ?

Answer 1

A straight angle measures 180°, so the three angles sum to 180°:

40 + (3x + 10) + (2x + 20) = 180
5x + 70 = 180
5x = 110
x = 22

(Check: angles are 40°, 76°, and 64°, which sum to 180°.)