Solution:
Note that:
Simplify the equation to find x.
Sum of angles=180
[tex]\\ \rm\bull\rightarrowtail 5x+7+4x+16+5x+17=180[/tex]
[tex]\\ \rm\bull\rightarrowtail 14x+40=180[/tex]
[tex]\\ \rm\bull\rightarrowtail 14x=140[/tex]
[tex]\\ \rm\bull\rightarrowtail x=10[/tex]