#### Explanation:

The best way to approach this type of question is as a direct proportion. You know that $15 represents 30% and need to know what value was the 100% $/% = 15/30 = x/100" "larr cross-multiply

$30 x = 15 \times 100$

$x = \frac{15 \times 100}{30}$

$x = 50$