3$\cdot$19 Given that 2 kg of apples, 1 kg of pears, and 4 kg of peaches cost 6 yuan, and 4 kg of apples, 2 kg of pears, and 2 kg of peaches cost 4 yuan. Now, if you want to buy 4 kg of apples, 2 kg of pears, and 5 kg of peaches, how much should you pay?
(A) 8 .
(B) 6 .
(C) 5 .
(D) 4 .
(1st "Five Sheep Cup" Junior High School Mathematics Competition, 1989)
[Solution] Let the price per kilogram of apples, pears, and peaches be $x, y, z$ yuan, respectively. According to the problem, we have
$$
\left\{\begin{array}{l}
2 x+y+4 z=6 \\
4 x+2 y+2 z=4 .
\end{array}\right.
$$
(1) $\times 2+$ (2) gives $8 x+4 y+10 z=16$, which simplifies to
$$
4 x+2 y+5 z=8 \text {. }
$$

Therefore, the correct choice is $(A)$.