Uprosti izraz: $$14\sqrt{15}:(2\sqrt{20}+\sqrt{45}-2\sqrt{245})$$.
$$...=\frac{14\sqrt{15}}{2\cdot 2\sqrt{5}+3\sqrt{5}-2\sqrt{49\cdot 5}}$$ $$=\frac{14\sqrt{15}}{4\sqrt{5}+3\sqrt{5}-14\sqrt{5}}$$ $$=\frac{14\sqrt{15}}{-7\sqrt{5}}$$ $$=\frac{-2\sqrt{3}\cdot \sqrt{5}}{\sqrt{5}}$$ $$=-2\sqrt{3}$$.