Respuesta :

Factors:

15 = 1, 3, 5, 15

21 = 1, 3, 7, 21

The GCF is 3

That means that you can take three out of 15 and 21

15/3 = 5

21/3 = 7

so...

3 (5 + 7)

Hope this helped!

~Just a girl in love with Shawn Mendes