(a+2s)-\frac{1}{2}(a-2s)=2(a+2s)-(a-2s)=2a+4s-a+2s=a+6s
3(3s+2f-292s+f)=3(3f-289s)=3f-867s
2x(a-b)+5(ax-bx)=2ax-2bx+5ax-5bx=7ax-7bx
7(ax-2)-4a(x-2)+2(ax+2)=7ax-14-4ax+8a+2ax+4=5ax+8a+10
2x(x+2)-(x^2+2x)-4=2x^2+4x-x^2-2x-4=x^2+2x-4
6xy-(2xy+3y)+(-xy+4x-7y)=6xy-2xy-3y-xy+4x-7y=3xy-10y+4x
(4a^2-3ab+b^2)-(-a^2-ab+b^2)-(4a^2-2b)=4a^2-3ab+b^2+a^2+ab-b^2-4a^2+2b=a^2-2ab+2b
(2a+5ab+3b)-(3a+5ab+1)-(-a+3b)=2a+5ab+3b-3a-5ab-1+a-3b=1