-7除以3-14除以3=-(7+14)÷3=-21÷3=-7(-3.5)/7/8*(-3/4) =3.5*8/7*3/4=4*3/4=3【(+1又3/4)-(-7/8)+(-7/12)】除以(-7/8)=(7/4+7/8-7/12)×(-8/7)=-7/4×8/7-7/8×8/7+7/12×8/7=-2-1+2/3=-2又1/3