a) \(\dfrac{2}{3}-\dfrac{5}{7}.\dfrac{14}{25}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{4}{15}\)
b) \(-\dfrac{2}{5}.\dfrac{5}{8}+\dfrac{5}{8}.\dfrac{3}{5}=\dfrac{5}{8}.\left(-\dfrac{2}{5}+\dfrac{3}{5}\right)=\dfrac{5}{8}.\dfrac{1}{5}=\dfrac{1}{8}\)
c) \(25\%-1\dfrac{1}{2}+0,5.\dfrac{12}{5}\)
\(=\dfrac{1}{4}-\dfrac{3}{2}+\dfrac{1}{2}.\dfrac{12}{5}=\dfrac{1}{4}-\dfrac{3}{2}+\dfrac{6}{5}=-\dfrac{5}{4}+\dfrac{6}{5}=-\dfrac{1}{12}\)
a)\(\dfrac{2}{3}-\dfrac{5}{7}\cdot\dfrac{14}{25}=\dfrac{2}{3}-\dfrac{5.2.7}{7.5.5}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10}{15}-\dfrac{6}{15}=\dfrac{4}{15}\)
b)\(-\dfrac{2}{5}\cdot\dfrac{5}{8}+\dfrac{5}{8}\cdot\dfrac{3}{5}=\dfrac{-2.5}{5.8}+\dfrac{5.3}{8.5}=-\dfrac{2}{8}+\dfrac{3}{8}=\dfrac{-2+3}{8}=\dfrac{1}{8}\)
c)\(25\%-1\dfrac{1}{2}+0,5\dfrac{12}{5}=\dfrac{25}{100}-\dfrac{3}{2}+\dfrac{29}{10}=\dfrac{5}{20}-\dfrac{30}{20}+\dfrac{58}{20}=\dfrac{5-30+58}{20}=\dfrac{33}{20}\)
