To convert the decimal 5.5 into a fraction:

1. Write it as a fraction:
   5.5 can be written as $\frac{5.5}{1}$.

2. Eliminate the decimal by multiplying both the numerator and denominator by 10:
   $\frac{5.5}{1} \times \frac{10}{10} = \frac{55}{10}$.

3. Simplify the fraction (if possible):
   The greatest common divisor (GCD) of 55 and 10 is 5. So, divide both the numerator and the denominator by 5:
   $\frac{55 \div 5}{10 \div 5} = \frac{11}{2}$.

Thus, the decimal 5.5 as a fraction is $\frac{11}{2}$.

Would you like more details or have any further questions? Here are some related questions:

1. How do you convert a repeating decimal into a fraction?
2. What is the process for simplifying fractions?
3. How can you convert fractions to decimals?
4. What are the steps for converting mixed numbers to improper fractions?
5. How can you convert decimals into percentages?

Tip: Always remember to multiply both the numerator and denominator by 10 for every decimal place you need to eliminate.