How do You Simplify Fractions?

There are improper fractions , proper fractions , mixed fractions with like denominators or unlike denominators.Consider the fractions 3 / 4 , 5 /4 if the operation is to add then (3+5)/4 = 8 / 4 = 2. If the fractions like 2 3/4 + 4 5/4 = 11/4 + 21 /4 = 32/4 = 8.