Firstly before I go over the necessary steps, you do know what an improper fraction is correct? Improper fractions are when the top number (numerator) is greater than the denominator.
Examples: 7/5 3/2 100/45
A mixed fraction is when a fraction obtains a whole number and a fraction. An example of this is presented in this very question, 5 5/9. Notice how '5' is by the fraction 5/9. This signals 5 is a whole number.
To change mixed to improper:
1: You must * or x (multiply) the whole number, in this case 5, to the denominator. Which is nine. That would give us the number 45.
2: After that, we simply add the numerator's value to the value we just gotten. I.e 45. That would be what? 50!
3: Then you just switch that answer with 9, and kick the 5 away. (Simpler bland terms: Put the new answer, which is 50, on top of the denominator.)