9分之4加()减2分之1等于4分之3解：9分之4加()等于4分之3加2分之19分之4加()等于4分之5()等于4分之5减9分之4()等于45分之29
9分之4加(29/36)减2分之1等于4分之33/4-4/9+1/2=29/36
5/9+3/4-1/2 =5/9+(3/4-1/2) =5/9+(3/4-2/4) =5/9+1/4 =20/36+9/36 =29/36
red
