Answer:
x = 11
Explanation:
all angles in a triangle will add up to 180.
So we can start with the equation:
(19 + x) + (7 + 8x) + angle str = 180.
we are given the angle stv. This angle equals 125.
the angle of a straight line is 180. In order to find the angle next to another angle like angle stv and str are, all you have to do is subtract the angle from 180.
So to find str:
180 - 125 = 55
we already have one of our angles which is 55
so the equation is now:
(19 + x) + (7 + 8x) + 55 = 180
now do some simple simplification:
(19 + x) + (7 + 8x) + 55 = 180
______________ -55_-55
(19 + x) + (7 + 8x) = 125
26 + 9x = 125
-26_____-26
9x = 99
99/9 = 11
x = 11
Therefore, x = 11