5.5 in fraction

0.5=1/2

so

$$5.5=5\frac{1}{2}$$

5.5 --> Note that if you multiply by 10, you get 55. To get back 5.5, you have to divide by 10. 

So, 5.5 --> 55/10.

You can simplify this by dividing both the numerator and denominator by 5:

55/10 --> 11/2.