## Basic College Mathematics (10th Edition)

Use ratios and cross multiplication to find the percent of total. $\frac{part}{whole}=\frac{percent}{100}$ A whole circle is $360^\circ$. $\frac{18}{360}=\frac{x}{100}\longrightarrow$ Cross multiply. $360x=(18)(100)\longrightarrow$ Simplify. $360x=1800\longrightarrow$ Divide both sides by 360 to solve for x. $360x\div360=1800\div360\longrightarrow$ Simplify. $x=5$