热心网友
回答时间:2024-01-20 13:31
19、
(1)(-7)+5+(-3)+4
=(-7)+(-3)+5+4
=-10+9
=-1
(2)(-4)+2又2/3+(-1/2)+(-2又2/3)
=(-4)+(-1/2)+2又2/3-2又2/3
=-4-1/2+0
=-4又1/2
20、
(1)-5+7-2+136-88
=2-2+136-88
=136-88
=48
(2)(-1/2)-(-1/6)+(-2/3)+(-4/5)
=-3/6+1/6-4/6-4/5
=-1-4/5
=-1又4/5
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