The GCF stands for greatest common factor. To represent a sum by its GCF we need to use the distributive property and we need to first find the GCF of the numbers. Let's break each number by its factors:

We now multiply the numbers that appear on both.

We now apply the distributive property:
You dont get duplicates in the set so although there are 2 red pens it only appears once in the set.
So the correct answer is D
Answer:
(D). 6.
Step-by-step explanation:
The number of parts = 1 + 10 = 11.
So 10/11 of the alloy is copper and 1/11 is aluminium.
So the answer is 1/11 * 66
= 66/11= 6 pound,s
I think the answer is D
if not then its C