Respuesta :

ab+ac=a(b+c)
a is common factor
factor

6ab=2*3*a*b
9bc=3*3*b*c
common factor is 3*b or 3b

3b(2a)+3b(3c)=3b(2a+3c)
3b(2a + 3c)       Both 6 and 9 are divisible by three and the b is in both parts of                             expression