除数和被除数同乘以12(5/6-3/4)÷(1/4+1/6) =[12×(5/6-3/4)]÷[12×(1/4+1/6) ]=(12×5/6-12×3/4)÷(12×1/4+12×1/6)=(10-9)÷(3+2)=1÷5=1/5
