Answer:
C
Step-by-step explanation:
The adjacent angle to the left of 9x is 180 - 9x ( straight angle )
180 - 9x and 3x are corresponding angles and are congruent , then
3x = 180 - 9x ( add 9x to both sides )
12x = 180 ( divide both sides by 12 )
x = 15
Then
∠ 1 and 180 - 9x are vertically opposite angles and are congruent, so
∠ 1 = 180 - 9(15) = 180 - 135 = 45° → C
