Work shown above! x = 7
To solve use the supplementary angle next to the unknown angle to find an expression for that unknown angle and use that with the expressions inside the triangle to set equal to 180 and solve for x.
hope this helps c:
The graph of

is shown in the graph below.
The graph is of ∩-shape when the constant

of the quadratic equation

is negative
D. the angles are alternate which means that they will add up to 180 so the answer is D
hope this helps :)
Change in y over change in x is key
(4-1)/(5-6)=3/-1
13. -3
(9-4)/(2-0)=5/2
14. 5/2
(1-(-2))/(-6-4)=3/-10
15. -3/10