Ta có:
\(\dfrac{2x}{3}=\dfrac{3y}{4}\Rightarrow y=\dfrac{4}{3}.\dfrac{2x}{3}=\dfrac{8x}{9}\)
\(\dfrac{2x}{3}=\dfrac{4z}{5}\Rightarrow z=\dfrac{5}{4}.\dfrac{2x}{3}=\dfrac{10x}{12}=\dfrac{5x}{6}\)
\(\Rightarrow x+y+z=x+\dfrac{8x}{9}+\dfrac{5x}{6}=49\)
Hay \(\left(18+16+15\right).\dfrac{x}{18}=49\).
tức là $x = 18 $
\(\Rightarrow y=16\)
và \(z=15\)