Răspuns:
26. a) -27+8=- 15
b) [tex]\frac{2}{5} -\frac{7}{9} -\frac{1}{15} -\frac{2}{45}[/tex]= [tex]\frac{(18-35-3-2)}{45}[/tex]= [tex]-\frac{22}{45}[/tex]
28 . 1024=32*32 1024 patrat perfect
29. a-15/100a=255
100a-15a= 255*15
85a= 255*15 a= 255*3: 17 = 45 lei
45 lei s-a ieftinit
30. MN= AM + AN= 4+5= 9
31. P= 4l l= 80:4 = 20 m
A= lxl= 20x20=400 [tex]m^{2}[/tex]= 4 ari =4 000 000 ha
32. 2abc= 2197 = 13x13x13
2abc= 2744= 14x14x14
33. 12*(n-8) = 8 *(n+8)
12n-96= 8n+64 12n-8n= 96+64
4n= 160 n= 160:4= 40 n= 40
35. a+b= 0.75 a= b+ 0,1(6)
a+b= [tex]\frac{3}{4}[/tex] a= b+ [tex]\frac{15}{9}[/tex]= b+ [tex]\frac{5}{3}[/tex]= (3b+5)/3
[tex]\frac{3b+5}{3} +b= \frac{3}{4}[/tex] aducem la acelasi numitor 12
12b+20 + 12b = 9
24b= 9-20 24b= - 11 b=- 11/24
a= 17/8
