146-- In how many ways can the set $\{a, b, c, d, e, f, g\}$ be partitioned into two three-element sets and one single-element set such that $\{a\}$ is missing? (1) $45$ (2) $50$ (3) $56$ (4) $60$ %% Page 9
\textbf{146--} In how many ways can the set $\{a, b, c, d, e, f, g\}$ be partitioned into two three-element sets and one single-element set such that $\{a\}$ is missing?
(1) $45$ \qquad (2) $50$ \qquad (3) $56$ \qquad (4) $60$
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