3.
[tex]a) \ 4(2x+3y-1) = 4\cdot2x+4\cdot 3y +4\cdot(-1) = 8x+12y-4[/tex]
[tex]b) \ 3(2x+4y+3)-2(1-4x+5y)+4(-2-3x+4y) =\\\\=3\cdot2x+3\cdot4y+3\cdot3 -2\cdot1-2\cdot(-4x)-2\cdot5y+4\cdot(-2) + 4\cdot(-3x)+4\cdot4y=\\\\6x+12y+9-2+8x-10y-8-12x+16y = 2x+18y -1[/tex]
[tex]c) \ \frac{1}{6}(12x-6y+18)+\frac{1}{4}(8x+4y-12)+0,5(4x-6y+8)=\\\\=\frac{1}{6}\cdot12x+\frac{1}{6}\cdot(-6y)+\frac{1}{6}\cdot18+\frac{1}{4}\cdot8x+\frac{1}{4}\cdot4y+\frac{1}{4}\cdot(-12) + 0,5\cdot4x+0,5\cdot(-6y)+0,5\cdot8=\\\\=2x-y+3+2x+y-3+2x-3y+4 = 6x-3y+4[/tex]
[tex]d) \ \frac{3x-9}{3} - \frac{4x+12}{4} = \frac{3(x-3)}{3} -\frac{4(x+3)}{4} = x-3-(x+3) = x-3-x-3 = -6[/tex]
