4. 144 If $x_{1}, x_{2}, x_{3}, x_{4}, x_{5}$ satisfy the following system of equations
$$
\left\{\begin{array}{l}
2 x_{1}+x_{2}+x_{3}+x_{4}+x_{5}=6, \\
x_{1}+2 x_{2}+x_{3}+x_{4}+x_{5}=12, \\
x_{1}+x_{2}+2 x_{3}+x_{4}+x_{5}=24, \\
x_{1}+x_{2}+x_{3}+2 x_{4}+x_{5}=48, \\
x_{1}+x_{2}+x_{3}+x_{4}+2 x_{5}=96 .
\end{array}\right.
$$

Find the value of $3 x_{4}+2 x_{5}$.
[Solution] Add up the five equations in the given system, then divide by 6, to get
$$
x_{1}+x_{2}+x_{3}+x_{4}+x_{5}=31 \text {. }
$$

Subtract (1) from the fourth equation in the system to get $x_{4}=17$.
Subtract (1) from the fifth equation in the system to get $x_{5}=65$.
Therefore, $3 x_{4}+2 x_{5}=3 \times 17+2 \times 65=181$.