Question

15 is 30% of what number?

Answer 1

0.5 times 100 = 50... 50 is your answer

Answer 2

$\displaystyle 15 = 30\% \cdot x \\ \\ x \cdot \frac{30}{100} =15 \\\\\\ x=15: \frac{30}{100} \\ \\ \\ x=\not15 \cdot \frac{100}{\not30} \\ \\ \\ x= \frac{100}{2} \\ \\ \\ x=50$