Question

Factor each expression 27-9x+15y

Answer 1

27 = 3 · 9
9x = 3 · 3x
15y = 3 · 5y

27 - 9x + 15y = 3(9 - 3x + 5y)

Answer 2

So to factorise 27-9x+15y you need the HCM (highest common factor) of 27, 9 and 15.
HCM: 3

So you divide each of the numbers by 3 and you get
27 divided by 3= 9
9 divided by 3= 3
15 divided by 3= 5

So you take the HCM (3) and then the numbers divided by it and put it into brackets

3(9-3x+5y)