Answer
$\begin{pmatrix} 7 \\ 2 \end{pmatrix}=21$
Work Step by Step
Seventh row of Pascal's triangle: $1~~7~~21~~35~~35~~21~~7~~1$
It corresponds to: $\begin{pmatrix} 7 \\ 0 \end{pmatrix}$ $\begin{pmatrix} 7 \\ 1 \end{pmatrix}$ $\begin{pmatrix} 7 \\ 2 \end{pmatrix}$ $\begin{pmatrix} 7 \\ 3 \end{pmatrix}$ $\begin{pmatrix} 7 \\ 4 \end{pmatrix}$ $\begin{pmatrix} 7 \\ 5 \end{pmatrix}$ $\begin{pmatrix} 7 \\ 6 \end{pmatrix}$ $\begin{pmatrix} 7 \\ 7 \end{pmatrix}$
So, $\begin{pmatrix} 7 \\ 2 \end{pmatrix}=21$
