756一(432一56一68)的简便运算:756 - (432 - 56 - 68)=756 - 432 + 68 + 56=756 - 556=200
=756-432+56+68=(756-432)+(56+68)=324+56+68=380+68=448
756一56一(432+68)=200
756一(432一56一68)简便运算?756-432+56+68=324-124=200
756-56-(432+68)