<|system|>
If $\mathbf{a} \times \mathbf{b} = \begin{pmatrix} 5 \\ 4 \\ -7 \end{pmatrix},$ then compute $\mathbf{a} \times (3 \mathbf{b}).$</s>.
<|user|>
Can you answer based on context?
<|assistant|>
Since the cross product is distributive,
\[\mathbf{a} \times (3 \mathbf{b}) = 3 (\mathbf{a} \times \mathbf{b}) = \begin{pmatrix} 15 \\ 12 \\ -21 \end{pmatrix}.\]