To find out the value of z we can use the formula
[tex]z=\frac{w+79}{2}[/tex]
But we also have to find out the value of w, which be found using the equation
[tex]360=x+79+w+60[/tex]
Which needs the value of x, which be found using
[tex]\frac{x+60}{2}=70[/tex]
But instead of doing all that and finding the value of x, w and z. We can directly find z using the fact that
Because it's all angles opposite by a vertex, and the sum of them all will be 360º, then we can say that
[tex]\begin{gathered} z+70+z+70=360 \\ \\ 2z+2\cdot70=360 \\ \\ 2z+140=360 \\ \\ 2z=360-140 \\ \\ 2z=220 \\ \\ z=\frac{220}{2} \\ \\ z=110 \end{gathered}[/tex]
Therefore, z = 110º.
