Đáp án:
Gọi số tiền mà Q, Hùng, N, H phải góp là a; b; c; d
\[\dfrac{a}{6}=\dfrac{b}{5}=\dfrac{c}{4}=\dfrac{d}{3}=\dfrac{a+b+c+d}{3+4+5+6}=\dfrac{720000 }{18}=40000(dong)\]
\[\rightarrow \left\{\begin{matrix}
a=40000\times 6=240000(dong) & \\
b=40000\times 5=200000(dong) & \\
c=40000\times 4= 160000(dong) & \\
d=40000\times 3=120000(dong) &
\end{matrix}\right.\]