154. The number of non-negative integer solutions of $4 \leq x_2 + x_3 \leq x_1 + x_2 + x_3$ is which of the following? (1) $35$ (2) $32$ (3) $33$ (4) $35$
\textbf{154.} The number of non-negative integer solutions of $4 \leq x_2 + x_3 \leq x_1 + x_2 + x_3$ is which of the following?
(1) $35$ \hfill (2) $32$
(3) $33$ \hfill (4) $35$
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