A.1又3/25+[(1.5+2又2/3)÷3又3/4-0.4]+8又8/9
=28/25+[(9/6+16/6)÷15/4-0.4]+80/9
=28/25+[(9/6+16/6)÷15/4-0.4]+80/9
=28/25+[10/9-10/25]+80/9
=10+18/25
=10又18/25
B.[(15/28-11/36)×21/29+6又2/7÷16/21]÷16又1/2
=[45/(4×29)-77/(12×29)+(44×21)/(7×16)]÷33/2
=[1/6+33/4]÷33/2
=1/99+1/2
=101/198
C.1-[(2又1/2-1又1/3)÷1又1/6]÷4又1/2+2又1/3
=1-[7/6÷7/6]÷9/2+7/3
=1-2/9+21/9
=1+19/9
=3又1/9
D.[1÷(3.1-3.09)]÷(1/3+0.8+8/15)
=100÷5/3
=60
E.1998×1999-1995×2002
=1998×1999-(1998-3)×(1999+3)
=1998×1999-(1998×1999-3×1999+1998×3-9)
=1998×1999-(1998×1999-12)
=12