Respuesta :

ncsftw

Answer:

3(7x + 5y)

Step-by-step explanation:

the highest common factor for this equation is 3, as 21/3 = 7 and 15/3 = 5, and 5 and 7 have no more common factors:

thus - > 21x + 15y = 3(7x + 5y)

2(x+7y)
I’m not sure about it