Answer:
∠ a = 119°
Step-by-step explanation:
Supplementary angles sum to 180° , then
6x + 17 + 3x + 10 = 180, that is
9x + 27 = 180 ( subtract 27 from both sides )
9x = 153 ( divide both sides by 9 )
x = 17
Then
∠ a = 6x + 17 = 6(17) + 17 = 102 + 17 = 119°
