The atomic weight of a newly discovered element is 10.600 amu. It has two naturally occurring isotopes. One has a mass of 10.000 amu and a natural abundance of 70.000%. What is the isotopic mass of the other isotope?

So, 10.600 (mass units) = 70%xx10.000 + 30%xxM_2; where ${M}_{2}$ is the isoptopic mass of the other isotope.
So solve for ${M}_{2}$! A priori would you expect ${M}_{2}$ to be larger or smaller than the mass of of the other isotope; why?