(1/12+1/2-7/12)÷1/7=(1/12+6/12-7/12)÷1/7=(-5/12-7/12)÷1/7=-1×7=-7
(1/12+1/2-7/12)÷1/7=(1/12+6/12-7/12)÷1/7=(7/12-7/12)÷1/7=0×7=0