Question

You must have a common denominator when ? fractions ​

Answer 1

You need to have common denominator when you are adding and subtracting you don’t need to a common denominator with multiplying and dividing

Answer 2

Explanation:

ADD::If the denominators are not the same, you must find the common denominator by finding the least common multiple of the 2.

SUBTRACT::If the denominators are not the same, you must find the common denominator by finding the least common multiple of the 2.