Question

5

Answer 1

first one is
\[\binom{5}{2}\times \binom{7}{3}\]

Answer 2

which really just restates the problem
\[\binom{5}{2}=\frac{5\times 4}{2}=10\] and \[\binom{7}{3}=\frac{7\times 6\times 5}{6\times 2}=7\times 5=35\]

Answer 3

typo there
\[\binom{7}{3}=\frac{7\times 6\times 5}{3\times 2}=35\]