Question

choose tools use a model to answer the question. use a proportion to check your answer. 15 is 30% of what number? 15 is 30% of \square

Explanation:

Step1: Define the variable

Let \( x \) be the number we are looking for. We know that 30% of \( x \) is 15. In mathematical terms, this can be written as \( 0.30x = 15 \) (since 30% is equivalent to 0.30 in decimal form).

Step2: Solve for \( x \)

To find \( x \), we divide both sides of the equation by 0.30. So, \( x=\frac{15}{0.30} \).

Step3: Calculate the value

Calculating \( \frac{15}{0.30} \), we get \( x = 50 \).

Step4: Check using proportion

We set up the proportion \( \frac{15}{x}=\frac{30}{100} \) (since 30% means 30 out of 100). Cross - multiplying gives us \( 30x=15\times100 \), which simplifies to \( 30x = 1500 \). Dividing both sides by 30, we have \( x=\frac{1500}{30}=50 \), which confirms our answer.

Answer:

\( 50 \)