4分之1÷75%=1/4÷3/4 =1/4×4/3 =1/3 7分之4×75% =4/7×3/4 =3/7 4分之1÷（2分之1-3分之1）÷2分之3 =1/4÷1/6÷3/2 =1/4×6×2/3 =1
求采纳