(1)3-8+3=8
(2)-4+7=3 (3)-6-9=-15 (4)8-12=-5
(5)-15+7=-8 (6)0-2=-2 (7)-5-9+3=-11 (8)10-17+8=1
(9)-3-4+19-11=1 (10)-8+12-16-23=-37
(11)-4.2+5.7+10=11.5(12)6.1-4.9+1.8=4.6
(13)-216-157+348+512-678
(14)81.26-293.8+8.74+111
(15)12-(-18)+(-7)-15=-2
不会还可以问我...