Giải thích các bước giải:
$\dfrac{\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}}{\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{1}{6}}:\dfrac{\dfrac{2}{5}\left(\dfrac{1}{4}+\dfrac{3}{7}+\dfrac{5}{9}\right)}{\dfrac{3}{20}+\dfrac{9}{35}+\dfrac{1}{3}}$ = $\dfrac{\dfrac{47}{60}$+$\dfrac{37}{60}$ : $\dfrac{\dfrac{2}{5}$ . \dfrac{311}{252}}{\dfrac{311}{420}}$
=$\dfrac{\dfrac{47}{60}}{\dfrac{37}{60}}$ : $\dfrac{\dfrac{311}{630}}{\dfrac{311}{420}}$
=$\dfrac{47}{37}$ : $\dfrac{2}{3}$
=$\dfrac{141}{74}$
#NoCopy