Explanation:
Problem 1)
The given angle is a right angle with measure 90° so
2x + x = 90°
3x = 90°
x = 30°
Problem 2)
The given angle is a straight angle with measure of 180°
2x + 3 + x - 6 = 180° add like terms
3x - 3 = 180°
3x = 183°
x = 61°
Problem 3)
The given angles are corresponding angles with same angle measurement
x + 16 = 4x - 5
21 = 3x
7 = x