(1)x*y+(y-x)*2=xy+x-y+2(y-x)+y-x-2=xy+2y-2x-2(2)x*y-(x+y)*x=1*2-3*1=1×2+1-2-(3×1+3-1)=1-5=-4
x*y-(x+y)*x=1*2-3*1=1×2+1-2-(3×1+3-1)=1-5=-4