1. The problem is to find the determinant of the 2x2 matrix $\begin{bmatrix} x & 3 \\ 7 & ? \end{bmatrix}$. However, the matrix is incomplete as the bottom right element is missing. 2. To calculate the determinant of a 2x2 matrix $\begin{bmatrix} a & b \\ c & d \end{bmatrix}$, the formula is: $$\text{det} = ad - bc$$ 3. Since the bottom right element is missing, we cannot compute the determinant without the full matrix. 4. Please provide the complete matrix or the missing element to proceed with the calculation.