[tex]\bf 2.\ \ \ \it \dfrac{a}{b}=\dfrac{3b}{b}=3.\\ \\ \\ \bf3.\ \ \ \it -2+a=2 \Rightarrow a=2+2=4\\ \\ \\ \bf4.\ \ \ \it\dfrac{2}{5}\cdot3=\dfrac{6}{5}\\ \\ \\ \bf5.\ \ \ \it m_a=\dfrac{7\sqrt3+21\sqrt3}{2}=\dfrac{28\sqrt3}{2}=14\sqrt3\\ \\ \\ \bf 6.\ \ \ \it \ b)\ fals\breve a\\ \\ (6\ caiete\ \d si\ 4\ pixuri\ cost\breve a\ 16\ \ell ei)[/tex]
