解1题：原式=(-1/63)÷(1/9-2/7+2/3-1/14)
=(-1/63)÷[(1/9+2/3)-(2/7+1/14)]
=(-1/63)÷(7/9-5/14)
=(-1/63)÷(53/126)
=(-1/63)×126/53
= -(1/63×126/53)
= -2/53
解2题：原式=(-12又2/3)÷1.25-(-8又1/3)÷(-1.25)+(+20又1/3)÷1.25
=-38/3×5/4-25/3×5/4+61/3×5/4
=[(-38/3)+(-25/3)+61/3]×5/4
=[(-63/3)+61/3]×5/4
=(-2/3)×5/4
= -(2/3×5/4)
= -5/6