What is the work behind S=(10-2)180?

$$\begin{array}{rll}
S&=&(10-2)180\\
S&=&(10-2)\times 180\\
S&=&8\times 180\\
S&=&1440 \qquad \qquad \mbox{OR}\\\\
S&=&(10-2)180\\
S&=&10*180-2*180\\
S&=&1800-360\\
S&=&1440\\
\end{array}\\$$

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