(1)(-8.2)+10+2+(-1.8)
=-8.2-1.8 +10+2
=-(8.2+1.8)+10+2
=-10+10+2
=2
(2)(-0.8+(-0.7)+(-2.1)+0.8+3.5
=-0.8-0.7-2.1+0.8+3.5
=-0.8+0.8+3.5 -0.7-2.1
=0.7
(3)4分之1+(-3分之2)+5分之4+(-4分之1)+(-3分之1)
=4分之1-3分之2+5分之4-4分之1-3分之1
=4分之1-4分之1-3分之2-3分之1+5分之4
=(4分之1-4分之1)-(3分之2+3分之1)+5分之4
=0-1+5分之4
=-5分之1
(4)(-0.5)+3又4分之1+2.75+(-5又2分之1)
=-0.5+3.75+2.75-5.5
=(3.75+2.75)-(0.5+5.5)
=6.5-6
=0.5