40x+(32-2x)x=70 40x+32x-2x^2=70-2x^2+72x-70=0x^2-36x+35=0(x-35)(x-1)=0x-35=0,x-1=0x=35,x=1
约去2乘法分配率,移项得x^2-36x+35=0x=1或x=35