能巧算的要巧算（急,明天就交了!）

100.1+10.82+0.18-90.01 =21
40-4.72-5.28 =30
（4.32-0.87）+（1.68-1.13）=4
81.1+36.57-（31.1-13.43） =100
25.46-4.67-5.33+4.54=20

100.1+10.82+0.18-90.01=100.1+(10.82+0.18)-90.01=100.1+11-90.01=21.09
40-4.72+5.28=40-(5-0.28)+5.28=40-5+0.28+5.28=40.56
4.32-0.87）+（1.68-1.13）=(4.32+1.68）-（0.87.+1.13）=6-2=4
81.1+36.57-（31.7-13.43）=81.1+36.57+13.43-31.7=81.1+40-31.7=89.4
25.46-4.67-5.33+4.54 =25.46+4.54 -(4.67+5.33 )=30-10=20

100.1+10.82+0.18-90.01=(100-90)+(10.82+0.18)+(0.1-0.01)=10+11+0.09=21.09
40-4.72-5.28 = 40-(4.72+5.28)=40-10=30
(4.32-0.87)+(1.68-1.13)=(4.32+1.68)-(0.87+1.13)=6-2=4
81.1+36.57-(31.7-13.43)=81.1-31.7+(36.57+13.43)=50-0.6+50=99.4
25.46-4.67-5.33+4.54 =(25.46+4.54)-(4.67+5.33)=30-10=20