questions 11. 12. and 13. i think i found x for 13 but im not so sure

SOLUTION:
Step 1:
For Question Number 12, we have the following:
Step 2:
The two indicated angles sum up to 180 degrees
so, we have that:
[tex]\begin{gathered} 5x\text{ + 16 + ( 9x - 4 ) = 180} \\ \text{collecting like terms, we have that:} \\ 5\text{ x + 9 x + 16 - 4 = 180} \\ 14\text{ x + 12 = 180} \\ 14\text{ x = 180 - 12} \\ 14\text{ x= 168} \\ \text{Divide both sides by 14 , we have that:} \\ x\text{ = }\frac{168}{14} \\ x\text{ = 12} \end{gathered}[/tex]CONCLUSION:
The value of x = 12