Step 1: Understand matrix multiplication rules.
A $3 \times 2$ matrix multiplied by an $m \times n$ matrix results in a $3 \times n$ matrix. Step 2: Compare with the result matrix.
The resulting matrix is $3 \times 3$.
So the second matrix must have 3 columns (n = 3).
Since the first matrix is $3 \times 2$, R must be $2 \times 3$ for multiplication to be valid. Step 3: Conclusion.
Thus, R is a $2 \times 3$ matrix.