A2. In the left triangle, the third angle is equal to 180-7 $x$ degrees. In the right triangle, the third angle is equal to 180-13 $x$ degrees. The two base angles of the middle triangle are each equal to one of those angles.

So it must be true that: $5 x+(180-7 x)+(180-13 x)=180$ thus $15 x=180$ and therefore $x=12$.
A2. In the figure, several angles are given in terms of $x$.

The value of $x$ in degrees is:
(A) 6
(B) 8 (C) 10
(D) 12
(E) 15

![](https://cdn.mathpix.com/cropped/2024_04_17_a3bc55bf766c62c14a9bg-1.jpg?height=349&width=737&top_left_y=1556&top_left_x=1139)