Average+Atomic+Mass

**Average Atomic Mass**
We have looked at how to calculate average atomic mass when knowing the percentage or relative abundance of each isotope. How do you calculate the percentage of each isotope when you have the average atomic mass? Assume you only have two known isotopes of each element. Save your thoughts here.

For example, if the average atomic mass for chlorine is 35.45, and the only two isotopes that chlorine forms is Cl-35 and Cl-37, what are the percentages for each isotope?

We have no clue at this point.

AMU (Nikki, Dina, Alyson) We are extremely confused, but we think it might have some division involved.