Question

find the missing number in the proportion
\frac{9}{15} = \frac{3}{x}
\quad x = \square

Explanation:

Step1: Cross - multiply the proportion

In a proportion \(\frac{a}{b}=\frac{c}{d}\), we have \(a\times d = b\times c\). For \(\frac{9}{15}=\frac{3}{x}\), cross - multiplying gives \(9\times x=15\times3\).

Step2: Simplify the right - hand side

Calculate \(15\times3 = 45\), so the equation becomes \(9x = 45\).

Step3: Solve for \(x\)

Divide both sides of the equation \(9x = 45\) by 9. That is \(x=\frac{45}{9}\).

Step4: Calculate the value of \(x\)

\(\frac{45}{9}=5\).

Answer:

\(x = 5\)