1. **State the problem:** We are asked to add two matrices $B$ and $C$ where $B = \begin{bmatrix} 2 & 1 \\ 1 & 2 \end{bmatrix}$ and $C = \begin{bmatrix} 7 & -1 & 5 \\ 0 & -3 & 3 \end{bmatrix}$. 2. **Recall the rule for matrix addition:** Two matrices can be added only if they have the same dimensions (same number of rows and columns). 3. **Check the dimensions:** - Matrix $B$ is $2 \times 2$ (2 rows, 2 columns). - Matrix $C$ is $2 \times 3$ (2 rows, 3 columns). 4. **Conclusion:** Since $B$ and $C$ do not have the same dimensions, matrix addition is **not defined** for these two matrices. **Final answer:** $$\text{Matrix addition is not possible because the matrices have different sizes.}$$