去括号=0.75-11/4+0.125-5/7-33/8 =3/4-11/4+1/8-5/7-33/8 =(3-11)/4+(1-33)/8-5/7 =(-8)/4+(-32)/8-5/7 =-2-4-5/7 =-6-5/7 =-6又5/7
