Question

solving propo step 1: write a proportion and use variable to represer the unknown numbe step 2: cross multiply step 3: solve for the variable solve each propor 1
\frac{15}{x} = \frac{21}{28}

Explanation:

Step1: Cross - multiply the proportion

Given the proportion \(\frac{15}{x}=\frac{21}{28}\), cross - multiplying means we multiply the numerator of the first fraction by the denominator of the second fraction and set it equal to the numerator of the second fraction multiplied by the denominator of the first fraction. So we get \(21\times x = 15\times28\).

Step2: Calculate the right - hand side

First, calculate \(15\times28\). \(15\times28 = 420\), so the equation becomes \(21x=420\).

Step3: Solve for \(x\)

To solve for \(x\), we divide both sides of the equation \(21x = 420\) by 21. So \(x=\frac{420}{21}\).

Step4: Simplify the fraction

Simplifying \(\frac{420}{21}\), we know that \(420\div21 = 20\).

Answer:

\(x = 20\)