(1)15.5+(-3又4/7)+(-5又1/2)+(-4又3/7)
=[15.5+(-5又1/2)]+[(-3又4/7)+(-4又3/7)]
=10+(-8)
=2
(2)1/2+(-2/3)+4/5+(-1/2)+(-1/3)
=[1/2+(-1/2)]+(-2/3)+(-1/3)+4/5
=0+(-1)+4/5
=-1/5
(3)2又2/4+0.25+(-2又1/4)+2又1/2+(-2.75)
=(2又2/4+2又1/2)+[(-2又1/4)]+(-2.75)]+0.25
=5+(-5)+0.25
=0.25