Transcript text: Solve for $x$.
When angles form a linear pair, their sum is $180^{\circ}$.
\[
\begin{array}{r}
8 x-3+4 x+3=180 \\
{[?] x+[]=180}
\end{array}
\]
Hint: First we must combine like terms. Calculate the sum of $8 x$ and $4 x$ and enter the value of the coefficient.