(1),(+1.25)+(-1/2)+(-3/4)+(+1又3/4)
=1.25-0.5-0.75+1.75
=0.75-0.75+1.75
=1.75
(2),(-0.5)-(3又1/4)+2.75-(+7又1/2)
=-0.5-3.25+2.75-7.5
=(-0.5-7.5)+(2.75-3.25)
=-8-0.5
=-8.5
(1),(+1.25)+(-1/2)+(-3/4)+(+1又3/4)
=1.25-0.5-0.75+1.75
=0.75-0.75+1.75
=1.75
(2),(-0.5)-(3又1/4)+2.75-(+7又1/2)
=-0.5-3.25+2.75-7.5
=(-0.5-7.5)+(2.75-3.25)
=-8-0.5
=-8.5