Let each of the needed angles be x. Express in an equation.

x+x+42=180

2x=180-42

\(\displaystyle{x}=\frac{{138}}{{2}}\)

x=69.

Each of the remaining angles is 69^circ

x+x+42=180

2x=180-42

\(\displaystyle{x}=\frac{{138}}{{2}}\)

x=69.

Each of the remaining angles is 69^circ