Trong 1 giờ, người ấy đi được số ki-lô-mét:

8 : \(\dfrac{2}{3}\) = 12 ( km )

       Đáp số : 12 km

a) \(\dfrac{3}{9}+\dfrac{9}{15}+\dfrac{8}{12}=\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{2}{3}=\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\dfrac{3}{5}=1+\dfrac{3}{5}=\dfrac{8}{5}\)

b) \(\dfrac{4}{10}+\dfrac{12}{32}+\dfrac{9}{15}=\dfrac{2}{5}+\dfrac{3}{8}+\dfrac{3}{5}=\left(\dfrac{2}{5}+\dfrac{3}{5}\right)+\dfrac{3}{8}=1+\dfrac{3}{8}=\dfrac{11}{8}\)

Doanh nhân

\(\dfrac{6}{7}>\dfrac{5}{7}\)

\(3\dfrac{3}{5}=\dfrac{3\times5+3}{5}=\dfrac{18}{5}\)