for adding or subtracting fractions, we make them like fractions.

Like fractions -  means the fractions with same denominator.

When denominators are same - we can easily add or subtract the numerators.

example

5/2 - 4/2  = (5-4)/2 = 1/2

1/2 + 1/3 = 3/6 + 2/6 =  (3+2)/6 = 5/6