6c+4d-c-7d
4a+7b+5a-b
3ab-9ab+7ab
this number is a multiple of seven and two is a foctor of 28
(x+2)(x+3)(x+4)=120
3c-9d+7c+5d
3/7+2/9
(A(x+2)-100x)*(x+2)
1/9+7/8
