30 is 15% of what number?
\(30 =15\% \ of \ x\\ \\ 30= \frac{15}{100}\cdot x \\ \\ 30= \frac{15x}{100} \\ \\ 15x=30\cdot100 \\ \\ 15x=3000\\\\ \boxed{\bold{x=200 }}\)
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