原式=(1/6-2/7+2/3-3/14)÷(-1/42)
=(1/6-2/7+2/3-3/14)×(-42)
=(1/6)×(-42)-(2/7)×(-42)+(2/3)×(-42)-(3/14)×(-42)
=-7+12-28+9
=(12+9)-(7+28)
=21-35
=-(35-21)
=-14