The element rhenium(RE) has two naturally occurring isotypes, 185Re and 187 Re, with an average atomic mass of 186.956 amu. Calculate the mass of 185 Re

The mass of 185Re = 185?? Do you mean the percentage of 185Re?

Let percentage oif 185Re = w, so percentage of 187Re = 100-w

The mass of 185Re = 185?? Do you mean the percentage of 185Re?

Let percentage oif 185Re = w, so percentage of 187Re = 100-w

(w/100) x 185 + ((100-w)/100) x 187 = 186.956

Solve for w