Respuesta :

if it is a fraction like (3a-3b)/(3a+12b)
= [3(a-b)]/[3(a+4b)]
= (a-b)/(a+4b)

3a-3b/3a+12b

Factor 3a-3b by 3

3(a-b)

Factor 3a+12b

3(4a+b)

3(a-b)/3(4a+b)

Cross out 3 and 3 , divide by 3

= a-b/4a+b

Answer: a-b/4a+b