432-(512-68)=432+68-512=500-512=-12
432一(512一68)简便方法?432一(512一68)=432-512+68=432+68-512=500-512=-12
=432+68-512=500-512=-12
去括号,432-512+68移项,432+68-512得出,500-512等于-12
432-[512-(100-32)]=432-[512-100+32]=432-32-[512-100]=400-412=-12