Respuesta :
Step-by-step 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.
You need to have common denominator when you are adding and subtracting you don’t need to a common denominator with multiplying and dividing