Calculate the expansion number and the denominator.

First, calculate the expansion number by dividing the two numerators.

Second, calculate the denominator by multiplying it with the expansion number.

If you would like to have a vivid explanation with a detailed example, please read the page Expanding Fractions - The cake must be enough for everyone

**Step 1: Calculate the Expansion Number**

To calculate the *expansion number*, divide the numerator of the expanded fraction (15) by the numerator of the first fraction (3):

Expansion Number: 15 ÷ 3 = 5

**Step 2: Calculate the denominator**

To calculate the *denominator* of the second fraction, multiply the denominator of the first fraction (5) by the expansion number (5):

Nenner: 5 × 5 = 25