Odpowiedź:
[tex]b)\ \ \frac{3x+9}{3}-\frac{2x-9}{4}=\frac{\not3^1(x+3)}{\not3_{1}}-\frac{2x-9}{4}=\frac{x+3}{1}-\frac{2x-9}{4}=\frac{4(x+3)}{4}-\frac{2x-9}{4}=\\\\=\frac{4x+12-(2x-9)}{4}=\frac{4x+12-2x+9}{4}=\frac{2x+21}{4}[/tex]
