Answer:
6
Explanation:
Knowing that the sum of angles on a straight is 180 degrees, let's go ahead and solve for x as shown below;
[tex]\begin{gathered} (20x+11)+(9x-5)=180\ldots\ldots\ldots\text{.(sum of angles on a straight line)} \\ 20x+9x=180-11+5 \\ 29x=174 \\ x=\frac{174}{29} \\ x=6 \end{gathered}[/tex]