To rewrite the sum \(6 + 12\) using their greatest common factor (GCF) and multiplication, we first need to find the GCF of \(6\) and \(12\).
The GCF of \(6\) and \(12\) is \(6\).
We can express \(6 + 12\) as follows:
\[ 6 + 12 = 6 \cdot 1 + 6 \cdot 2 = 6(1 + 2) \]
So the correct answer is:
6(1 + 2).