(a-2)*(x-4)=
(x+2)*(a-7)=
(a+4)*(3a-2)=
(6-b)*(b+2)=
(3-3y)*(2y-5)=

(a-2)*(x-4)=ax-4a-2x+8
(x+2)*(a-7)=ax-7x+2a-14
(a+4)*(3a-2)=3a²-2a+12a-8=3a²+10a-8
(6-b)*(b+2)=6b+12-b²-2b=-b²+4b+12
(3-3y)*(2y-5)= 6y-15-6y²+15y=-6y²+21y-15