The rule for dividing fractions is "invert and multiply." What you invert is the denominator fraction.
Example: (1/3) / (4/5) = (1/3)×(5/4) . . . . . the denominator 4/5 has been inverted to 5/4 and is now a multiplier.
All the rest of the rules for fractions are unaltered--conversion from mixed numbers to improper fractions, addition and subtraction--they're all the same.