Answer
See below.
Work Step by Step
We know that ${n\choose j}=\frac{n!}{(n-j)!j!}$.
Hence here ${5\choose 3}=\frac{5!}{(5-3)!3!}=\frac{5\cdot4\cdot3\cdot2\cdot1}{2\cdot1\cdot3\cdot2\cdot1}=10$.
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