Find the greatest common factor of 36 and - 81. A) 3 B) 6 C) 9 D) 18

Well, i'm assuming you meant to put 81 instead of - 81.

Let's look at the factors of 36.

We've got 1, 2, 3, 4, 6, 9, 12, 18, and 36

These are all dividable into 36.

Then, we have the factors of 81.

1, 3, 9, 27, 81.

Again, all dividable into 81.

So the largest number that's in common with both of these sets is 9.

Your GCF is 9.

The answer is D because 9 can go into 36 4 times and 9 can go into 81 9 times