we know that
total of sum of arc is 360
so, sum of both arc must be 360
so, we get

now, we can solve for x

............Answer
Answer: C
Step-by-step explanation:
We can use the expanding rule to get that one if the expressions is
(9x^2 + 2x - 7)x + (9x^2 + 2x - 7)(-4)