Tìm x, biết: \(\Large\dfrac{2}{5}:\dfrac{x}{3}:\dfrac{7}{4}=\dfrac{24}

Tìm x, biết:

\(\Large\dfrac{2}{5}:\dfrac{x}{3}:\dfrac{7}{4}=\dfrac{24}{315}\) 

• A. 3
• B. 5
• C. 7
• D. 9

\(\Large\dfrac{2}{5}:\dfrac{x}{3}:\dfrac{7}{4}=\dfrac{24}{315}\) 

\(\Large\dfrac{2}{5}:\dfrac{x}{3}=\dfrac{24}{315}\times\dfrac{7}{4}\) 

\(\Large\dfrac{2}{5}:\dfrac{x}{3}=\dfrac{2}{15}\) 

\(\Large\dfrac{x}{3}=\dfrac{2}{5}:\dfrac{2}{15}\) 

\(\Large\dfrac{x}{3}=\dfrac{2}{5}\times\dfrac{15}{2}\) 

\(\Large\dfrac{x}{3}=3\) 

\(\Large\dfrac{x}{3}=\dfrac{9}{3}\) 

\(\Large x=9\)