Câu trả lời:

\(a,\frac{a}{2}=\frac{b}{3}=\frac{c}{4}\Rightarrow\frac{a}{2}=\frac{2b}{6}=\frac{3c}{12}\)

\(\Leftrightarrow\frac{a+2b-3c}{2+6-12}=\frac{-20}{-4}=5\)

Vậy: \(a=5.2=10\)

\(b=5.6:2=15\)

\(c=5.12:3=20\)