# Title
\begin{align}
S(x)=\begin{cases}
-4x+31 &\quad\text{if} \quad 0\le x \le12\\
295 &\quad\text{if} \quad 12< x \le20\\
\frac{3}{4}x+278.5 &\quad\text{if} \quad 20< x \le30\\
\frac{3}{2}x+404 &\quad\text{if} \quad 30< x <40\\
\end{cases}
\end{align}

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