12a+15b=3(4a+5b)

ab-ay=a(b-y)

a^3p-a^2=a^2(ap-1)

4ac^2+8a^2c^2=4ac^2(1+2a)

(2+X)+A(2+X)=(2+X)(1+A)

3x(a+b)+y(a+b)=(a+b)(3x+y)

m(x-y)-(x-y)=(x-y)(m-y)

(c+2)-d(c+2)=(c+2)(1-d)

5p(r-s)+6q(r-s)=(r-s)(5p+6q)

15c(a+b)+8(b+a)=(a+b)(15c+8)

n(2a+1)+m(1+2a)=(2a+1)(n+m)

4a(x+y)-9b(y+x)=(x+y)(4a-9b)

11p(c+8d)-9(8d+c)=(c+8d)(11p-9)

a(b-c)+3(c-b)=a(b-c)-3(b-c)=(b-c)(a-3)

6(m-n)+s(n-m)=6(m-n)-s(m-n)=(m-n)(6-s)

4(p-q)-a(q-p)=4(p-q)+a(p-q)=(p-q)(4+a)

7z(x-y)-5(y-x)=7z(x-y)+5(x-y)=(x-y)(7z+5)