方法一：(x-8)(-20+400)=640(x-8)*380=640(x-8)*19=3219x-152=3219x=32+15219x=184x=184/19方法二：(x-8)(-20+400)=640(x-8)*380=640380x-3040=640380x=640+3040380x=3680x=184/19