\(\frac{x}{15}=\frac{y}{20}=\frac{z}{24}\Leftrightarrow\int^{\frac{2x}{30}=\frac{3y}{60}=\frac{4z}{96}}_{\frac{3x}{45}=\frac{4y}{80}=\frac{5z}{120}}\)
Theo t/c tỉ lệ tức ta có:
\(\frac{2x+3y+4z}{30+60+96}=\frac{3x+4y+5z}{45+80+120}\Leftrightarrow\frac{2x+3y+4z}{3x+4y+5z}=\frac{30+60+96}{45+80+120}=\frac{186}{245}\)
Vậy M=186/245