a,\(\dfrac{4}{9},\dfrac{17}{13}\)

b,\(\dfrac{12}{21},\dfrac{36}{63},\dfrac{48}{84}\)

\(\dfrac{12}{21}\) đúng nha

\(\dfrac{8}{11},\dfrac{17}{21},\dfrac{7}{8}\)

\(\dfrac{45}{60},\dfrac{27}{36},\dfrac{6}{8}\)

Cả hai vòi chảy cùng 1 giờ thì được là:

     \(\dfrac{1}{2}+\dfrac{1}{3}=\dfrac{5}{6}\left(bể\right)\)

         Đáp số:\(\dfrac{5}{6}bể\)

a,\(\dfrac{7}{4}\)

b,\(\dfrac{1}{3}\)

c,\(\dfrac{1}{7}\)

\(x+\dfrac{1}{3}=1\)

        \(x=1-\dfrac{1}{3}\)

        \(x=\dfrac{2}{3}\)

A.\(\dfrac{27}{5}m\)

C.\(\dfrac{17}{15}m\)