To add or subtract fractions with different denominators, you need to find a common denominator. Here are the steps to follow:

1. Find the least common multiple (LCM) of the denominators. This is the smallest number that both denominators divide into evenly.

2. Rewrite each fraction with the common denominator. To do this, multiply the numerator and denominator of each fraction by the same number that will make the denominator equal to the LCM.

3. Once the fractions have the same denominator, you can add or subtract the numerators.

4. Simplify the resulting fraction, if necessary, by reducing it to its simplest form.

Let’s look at an example:

Example: Add 1/4 and 2/3.

Step 1: Find the LCM of 4 and 3. The multiples of 4 are 4, 8, 12, 16, 20, 24, … and the multiples of 3 are 3, 6, 9, 12, 15, 18, 21, 24, … The LCM of 4 and 3 is 12.

Step 2: Rewrite each fraction with the common denominator of 12.

1/4 = (1 * 3)/(4 * 3) = 3/12

2/3 = (2 * 4)/(3 * 4) = 8/12

Step 3: Add the numerators.

3/12 + 8/12 = 11/12

Step 4: The fraction 11/12 is already in its simplest form, so the final answer is 11/12.

Therefore, 1/4 + 2/3 = 11/12.