We consider the revenue function $R(x)=10x$ and the cost function $C(x)=8x+30$ and we determine the break-even point.
This implies the following:
$$\begin{align}
R(x) = C(x) & \Leftrightarrow 10x=8x+30\\
& \Leftrightarrow 2x=30\\
& \Leftrightarrow x=15.
\end{align}$$
Hence, the break-even point is $x=15$.
This implies the following:
$$\begin{align}
R(x) = C(x) & \Leftrightarrow 10x=8x+30\\
& \Leftrightarrow 2x=30\\
& \Leftrightarrow x=15.
\end{align}$$
Hence, the break-even point is $x=15$.