3(х-4) (х+2) + (3х-1) (5-х)

3(x2+2x-4x-8)+(15x-3x2-5+x)=3x2+6x-12x-24+15x-3x2-5+x=10x-29

3(х-4) (х+2) + (3х-1) (5-х)=(3x-12)*(x+2)+15x-3x^2-5+1x==3x^2+6x-12x-24+15x-3x^2-5+1x==6x-12x-24+15x-5+x==10x-29