Step 1

Let's write down these fractions:

From here, we can see that these fractions have unlike denominators.

Step 2

Since the denominators are not the same, we must make them the same before we are able to add them. To do so, we can use the ideas behind Equivalent Fractions.

To find the equivalent fractions, we can multiply ²/₃ with the other fraction's denominator and vice versa. By doing so, both fractions will have like denominators. This is shown below:

Step 3

Now, with both fraction have like denominators. We can proceed by adding these fractions. This will result in the fraction ¹⁹/₁₅:

Step 4

Notice that ¹⁹/₁₅ is an improper fraction. Even though there is nothing wrong leaving it like this, it is advisable to change this fraction to a mixed fraction..

We can do so by performing a long division on ¹⁹/₁₅ as shown below:

Step 5

After conversion, we get the mixed fraction, 1 ⁴/₁₅. Clearly, the answer is D.