, 2016

Solution 1

Since $x\%$ of 60 is 12, then $\dfrac{x}{100}\cdot 60 = 12$ or $x = \dfrac{12\cdot 100}{60} = 20$.

Therefore, $15\%$ of $x$ is 15% of 20, or $0.15 \cdot 20 = 3$.

Solution 2

Since $x\%$ of 60 is 12, then $\dfrac{x}{100}\cdot 60 = 12$ or $\dfrac{60x}{100} = 12$.

In terms of $x$, 15% of $x$ equals $\dfrac{15}{100}x$ or $\dfrac{15x}{100}$.

Since $\dfrac{60x}{100} = 12$, then $\dfrac{15x}{100} = \dfrac{1}{4}\left(\dfrac{60x}{100}\right) = \dfrac{1}{4}\cdot 12 = 3$.