Calculation of Mass!
 

Hello @ all,

I am new here and i cannot solve the following Calculation.
I hope you all can help me!

I dont think it is sooo difficult but i dont get it.

The Question is :

Calculate the monoisotopic mass (electic neutral) of a peptide which is detekted in a ESI mass spectrum at m/z 660,67 and its isotopes in an distance of 0,33.

So I cannot solve the problem but i have to do it cause it is a task for my work :(

Thnk you ...

Best
Simon