Given the sum 99=33+66 , rewrite 33+66 using their GCF and multiplication.

The GCF of 33 and 66 is 33.

We can rewrite 33 + 66 using their GCF and multiplication as:
33 + 66 = 33(1) + 33(2) = 33(1 + 2) = 33(3).