求有理数加法和减法的简单拖式计算,要答案!

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19
解1：1+19=20 2+18=20 有9个 20相加在加中间的10本题等于190
解2：64+28+36+72
90-（72-70）=90-2=88
42+（33+7）=42+40 =82
78-（36-6）=78-30=48
75-20+40 =55+40=95
88-8+60 =80+60 =140
70-（48+2）=70-50=20
(45-17)+(9-3)=28+6=34, (45-17)+(9-6)=28+3=31, (45-18)+(9-3)=27+6=33
(45-18)+(9-6)=27+3=30, (45-27)+(9-3)=18+6=24, (45-27)+(9-6)=18+3=21
(45-28)+(9-3)=17+6=23, (45-28)+(9-6)=17+3=20, (46-17)+(8-3)=29+5=34
(46-17)+(8-5)=29+3=32, (46-19)+(8-3)=27+5=32, (46-19)+(8-5)=27+3=30
(46-27)+(8-3)=19+5=24, (46-27)+(8-5)=19+3=22, (46-29)+(8-3)=17+5=22
(46-29)+(8-5)=17+3=20, (54-16)+(9-2)=38+7=45, (54-16)+(9-7)=38+2=40
(54-18)+(9-2)=36+7=43, (54-18)+(9-7)=36+2=38, (54-36)+(9-2)=18+7=25
(54-36)+(9-7)=18+2=20, (54-38)+(9-2)=16+7=23, (54-38)+(9-7)=16+2=18
(57-18)+(6-2)=39+4=43, (57-18)+(6-4)=39+2=41, (57-19)+(6-2)=38+4=42
(57-19)+(6-4)=38+2=40, (57-38)+(6-2)=19+4=23, (57-38)+(6-