[tex]Zadanie\ 5\\\\a)\\\\(-2y)(3x+y)-2x(x-y)=-6xy-2y^2-2x^{2}+2xy=-2x^{2} -2y^2-4xy \\\\b)\\\\\frac{3x+9}{3}-\frac{2x-9}{4}=\frac{4(3x+9)-3(2x-9)}{12}=\frac{12x+36-6x+27}{12}= \frac{6x+63}{12}=\frac{1}{2}x+5\frac{3}{12}=\frac{1}{2}x+5\frac{1}{4}[/tex]
