Assuming a diagram similar to the one I've attached, ∠YVZ is a vertical angle to ∠WVX, which means they have an equal measure. Additionally, ∠WVZ and ∠WVX form a linear pair, which means they are supplementary (sum to 180°). That means we start out with the equation
[tex](11x-19)+(8x+28)=180[/tex]
We combine our like terms (the x's get combined, then the constants get combined) and have:
[tex]19x+9=180[/tex]
Cancel the 9 first by subtraction:
[tex]19x+9-9=180-9 \\ 19x=171[/tex]
Cancel the 19 by division:
[tex] \frac{19x}{19}= \frac{171}{19} \\ x=9[/tex]
Since we know that our angle we're looking for, ∠YVZ, is the same measure as ∠WVX, we substitute 9 in for x:
8(9)+28=72+28=100°
