[VIP] Вычислить несложный пример

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$0,1*\sqrt{20}:\sqrt{45}-2\frac{17}{30}= \\\\ =\frac{1}{10}*\frac{\sqrt{20}}{\sqrt{45}}-2\frac{17}{30}= \\\\ =\frac{1}{10}*\sqrt{\frac{20}{45}}-2\frac{17}{30}= \\\\ =\frac{1}{10}*\sqrt{\frac{4}{9}}-2\frac{17}{30}= \\\\ =\frac{1}{10}*\frac{2}{3}-2\frac{17}{30}= \\\\ =\frac{1}{15}-\frac{77}{30}= \\\\ =\frac{2}{30}-\frac{77}{30}= \\\\ =-\frac{75}{30}= \\\\ =-\frac{5}{2}= \\\\ =-2\frac{1}{2}=-2,5$