Given:
The objective is to find the value of x.
By the property of center axiom, the sum of adjacent angles of a straight line is always 180 degree.
[tex]\begin{gathered} 7x+x+20=180^0 \\ 8x+20=180 \\ 8x=180-20 \\ 8x=160 \\ x=\frac{160}{80} \\ x=20 \end{gathered}[/tex]
Hence, the value of x is 20.
