Notice that the angles of 140° and (8x)° are supplementary angles, since they make an angle of 180°. Then:
[tex]8x+140=180[/tex]
Solve for x:
[tex]\begin{gathered} \Rightarrow8x=180-140 \\ \Rightarrow8x=40 \\ \Rightarrow x=\frac{40}{8} \\ \Rightarrow x=5 \end{gathered}[/tex]
Therefore, the value of x is:
[tex]5[/tex]
