一.( -3.1) — ( -4.5) + (+4.4) — (+1.3) + ( -25 )
=-3.1+4.5+4.4-1.3-25
=-20.5
二.(+1/2) - (+5) + (-1/3) - (+1/4) + (5又2/3)
=1/2-5-1/3-1/4+5又2/3
=7/12
三.-4.2 + 5.7 - 7.6 + 10.1 - 5.5
=-1.5
一.( -3.1) — ( -4.5) + (+4.4) — (+1.3) + ( -25 )
=-3.1+4.5+4.4-1.3-25
=-20.5
二.(+1/2) - (+5) + (-1/3) - (+1/4) + (5又2/3)
=1/2-5-1/3-1/4+5又2/3
=7/12
三.-4.2 + 5.7 - 7.6 + 10.1 - 5.5
=-1.5