Percent Abundance of Isotopes

Question: 

Stupidium is a fictional element with 2 isotopes, \(^35\)St with a mass of 34.9567 g/mol, and \(^39\)St with a mass of 39.0095 g/mol. The molar mass of St is 35.9826 g/mol. What are the percent abundances of the isotopes?

Subject: 
General Chemistry 1›Chemical Formulas