Answer:
x = 31 and x = 15
Step-by-step explanation:
(a)
(3x + 31) and (2x - 6) are a linear pair and sum to 180° , then
3x + 31 + 2x - 6 = 180
5x + 25 = 180 ( subtract 25 from both sides )
5x = 155 ( divide both sides by 5 )
x = 31
(b)
3x and (4x - 15) form a right angle and sum to 90° , then
3x + 4x - 15 = 90
7x - 15 = 90 ( add 15 to both sides )
7x = 105 ( divide both sides by 7 )
x = 15
