\(\dfrac{2}{3}-\dfrac{5}{7}.\dfrac{14}{25}\)

\(=\dfrac{2}{3}-\dfrac{2}{5}\)

\(=\dfrac{4}{15}\)

Bài này dễ mà bạn

\(\dfrac{2}{7}.\dfrac{4}{5}+\dfrac{3}{5}.\dfrac{2}{7}-\dfrac{1}{5}\)

\(=\dfrac{8}{35}+\dfrac{6}{35}-\dfrac{1}{5}\)

\(=\dfrac{2}{5}-\dfrac{1}{5}\)

\(=\dfrac{1}{5}\)

Ta có :

25