To add the fractions $\frac{9}{10}$ and $\frac{3}{100}$, we need a common denominator.

Step 1: Find the least common denominator (LCD).

The denominators are 10 and 100. The least common denominator (LCD) is 100.

Step 2: Convert $\frac{9}{10}$ to an equivalent fraction with denominator 100.

Multiply both the numerator and denominator of $\frac{9}{10}$ by 10: $\frac{9}{10} = \frac{9 \times 10}{10 \times 10} = \frac{90}{100}$

Step 3: Add the two fractions.

Now, we can add $\frac{90}{100}$ and $\frac{3}{100}$: $\frac{90}{100} + \frac{3}{100} = \frac{90 + 3}{100} = \frac{93}{100}$

So, the sum of $\frac{9}{10}$ and $\frac{3}{100}$ is: $\frac{93}{100}$

Let me know if you'd like more details or have any questions!

Additional questions:

1. How do you add fractions with different denominators?
2. What is the process for simplifying fractions?
3. How do you convert a fraction to a decimal?
4. What is the difference between a proper and improper fraction?
5. How do you subtract fractions with different denominators?

Tip:

Always find the least common denominator (LCD) when adding or subtracting fractions with different denominators.