1.-5+(-15)=-20
2.-3+(-101)=-101
3.-123(-877)=-1000
4.-1+(-153)=-154
5.-654(-5)=-659
6.-3/7+(-4/7)=-1
7.-3 6/9+(-6 3/9)=-10
8.-5,75+(-4,25)=-10.
9.-1+(-1)=-2
10. 5-(-10)=15
11. -5+10=5
12. -3/7+4/7=1/7
13. 5,65-(-4,65)=10,3
14. 7/9-(-8/9)=1 2/3
15. 123+(-123)=0
16. 87-(-7/19)=87 7/19
17. 54,05-(-45,95)=100
18. -346+345=1
19. -54-(-54)=0
20. -1000+90=930
42/720 = 14/ 240 = 7/120
100/250 = 10/25 = 2/5
<span> (7a - 5b)(7a + 5b) - (4a + 7b)² = 49a² - 25b² - (16a² + 56ab + 49b²) =
= 49a² - 16a² - 25b² - 49b² - 56ab = 33a² - 74b² - 56ab
</span>
72:2=36;72:3*2=48;72:4*3=54;72*2=144;144+36=180
709.602+290.498=1.000.100
569.487.652+40.513.349=610.001.001
200.010.030-199.879.078=130.952
2.704.608.079-296.392.927=2.408.215.152
8640:8=1080
5250:5=1050
178:2=89
18*32=576
6293:31=203
2932-2782=150
121.350-115.325=6.025
6.025:5=1.205
5100:170=30
110.292:14=7.878
7878:101=78
78*231=18.018
90*3=270
25*25=625
30000000*40=1200000000
98-79=19
121-76=45
654-398=256
126+3395=3521