To add the fractions $\frac{2}{9}$ and $\frac{3}{18}$, we first need to ensure they have a common denominator.

The least common denominator (LCD) of 9 and 18 is 18. Now, let's rewrite $\frac{2}{9}$ with 18 as the denominator.

$\frac{2}{9} = \frac{2 \times 2}{9 \times 2} = \frac{4}{18}$

Now, we can add the two fractions:

$\frac{4}{18} + \frac{3}{18} = \frac{4 + 3}{18} = \frac{7}{18}$

So, the sum of $\frac{2}{9}$ and $\frac{3}{18}$ is $\frac{7}{18}$.

Would you like further clarification or have any questions about this? Here's a tip:

Tip: Always try to simplify fractions as much as possible before adding or subtracting.

Here are 5 related questions to explore:

1. What is the greatest common divisor (GCD) of 9 and 18?
2. How do you simplify fractions before performing operations like addition or subtraction?
3. What is the least common denominator (LCD) and how do you find it?
4. Can you add fractions with different denominators directly without adjusting the denominators?
5. How do you subtract fractions with different denominators?