Odpowiedź:
[tex]a)\ \ 49\dfrac{7}{13}:7\cdot\dfrac{1}{2}=\dfrac{\not644^9^2}{13}\cdot\dfrac{1}{\not7_{1}}\cdot\dfrac{1}{2}=\dfrac{\not92^4^6}{13}\cdot\dfrac{1}{\not2x_{1}}=\dfrac{46}{13}=3\dfrac{7}{13}\\\\\\b)\ \ \left(-2\dfrac{1}{2}\right):1\dfrac{2}{3}-1,4\cdot\left(-1\dfrac{3}{7}\right)+\dfrac{1}{9}=-\dfrac{5}{2}:\dfrac{5}{3}+\dfrac{\not14^2}{\not10_{1}}\cdot\dfrac{\not10^1}{\not7_{1}}+\dfrac{1}{9}=[/tex]
[tex]=-\dfrac{\not5}{2}\cdot\dfrac{3}{\not5}+2+\dfrac{1}{9}=-\dfrac{3}{2}+2+\dfrac{1}{9}=-1\dfrac{1}{2}+2+\dfrac{1}{9}=\dfrac{1}{2}+\dfrac{1}{9}=\dfrac{9}{18}+\dfrac{2}{18}=\dfrac{11}{18}[/tex]
[tex]c)\ \ \dfrac{1}{2}:\dfrac{1}{2}\cdot2=1\cdot2=2\\\\\\d)\ \ -(-1-3)^2:\dfrac{3}{5}=-(-4)^2:\dfrac{3}{5}=-16\cdot\dfrac{5}{3}=-\dfrac{80}{3}=-26\dfrac{2}{3}\\\\\\e)\ \ (-2)^3\cdot0,25+2\dfrac{1}{2}=-8\cdot0,25+2\dfrac{1}{2}=-2+2\dfrac{1}{2}=\dfrac{1}{2}[/tex]