①原式=(-9)×(3+7)=(-9)×10=-90
②原式=(5/4)×(-8/7)+(7/6)×(8/7)=-10/7+4/3=-2/21
③原式=(-54)×(1/6)×(-1/3)=-9×(-1/3)=3
④原式=2×(5-8)=-6
⑤原式=-〔(2/13)×78-(1/3)×78-(1/6)×78〕=-(12-26-13)=-(-27)=27
①原式=(-9)×(3+7)=(-9)×10=-90
②原式=(5/4)×(-8/7)+(7/6)×(8/7)=-10/7+4/3=-2/21
③原式=(-54)×(1/6)×(-1/3)=-9×(-1/3)=3
④原式=2×(5-8)=-6
⑤原式=-〔(2/13)×78-(1/3)×78-(1/6)×78〕=-(12-26-13)=-(-27)=27