A mixed number can only make improper fractions. Basically, improper fractions are fractions where the number on top is bigger than the one on the bottom. To find it, you multiply the denominator by the whole number, then add the numerator. Here's an example:
[tex]2 \frac{3}{5} [/tex].
5*2 is 10.
10+3 = 13.
You put that over the same denominator, which is 5. The answer to this problem would be [tex] \frac{13}{5} [/tex]