To factor using the reverse of the distributive property, find what common factor the numbers have and what common factor the variables have.
10.
-8x - 16
8 is a factor of both -8 and 16.
The first term has x, but the second term does not, so there is no common variable. The only common factor is 8, or -8.
Factor out a -8:
-8x - 16 = -8(x + 2)
To see if the factorization is correct, multiply the answer using the distributive property. If you get the original expression, then the factorization is correct.
11.
w^2 - 4w
The first term only has a factor of 1. The second term has a 4. There is no common factor between 1 and 4 except for 1, so there is no number you can factor out. The first term has w^2. The second term has w. Both terms have a common factor of w. We can factor out w from both terms.
w^2 - 4w = w(w - 4)
12.
4s + 10rs
4 and 10 have a common factor of 2.
s and rs have a common factor of s.
2 times s is 2s, so the common factor is 2s.
We now factor out 2s
4s + 10rs = 2s(2 + 5r)