10x = 15y + 5 (by the vertical angle theorem).
8x + 1 + 7y + 10x = 180 ( by triangle sum theorem)
18x + 7y = 179 .............(1)
from first equation :-
10x - 15y = 5.................(2)
Multiply (1) by 10 and (2) by -18:-
180x + 70y = 1790
-180x + 270y = -90
Adding :-
340y = 1700
y = 5
and from first equation
10x = 15(5) + 5 = 80
x = 8
Answer x=8, y = 5.
