Question

Why do fractions need to have a common denominator before you add or subtract them

Answer 1

So it will be easier to solve the answer that way rather than a huge number

Answer 2

It's easy to add and subtract like fractions, or fractions with the same denominator. You just add/subtract the numerators and keep the same denominator. The hard part is when you add or subtract fractions that have different denominators. To do this, you should know how to find the least common denominator