Câu hỏi 199
Tìm $a+b+c+d+e$ nếu
$$
\begin{gathered}
3 a+2 b+4 d=10, \\
6 a+5 b+4 c+3 d+2 e=8, \\
a+b+2 c+5 e=3, \\
2 c+3 d+3 e=4, \text{và} \\
a+2 b+3 c+d=7 .
\end{gathered}
$$
$$
\begin{gathered}
3 a+2 b+4 d=10, \\
6 a+5 b+4 c+3 d+2 e=8, \\
a+b+2 c+5 e=3, \\
2 c+3 d+3 e=4, \text{và} \\
a+2 b+3 c+d=7 .
\end{gathered}
$$