Sphere mass vs. surface area

If you have two spheres, one of them has a mass of 100 and a surface area of
100, and the other one has a surface area that is 70% less than the first
and has the same density, how much mass will the second sphere have?

I'm looking into this hypothesis (for fun ONLY) that when all the continents
were together, they made up the entire surface of the earth, and their
splitting and drifting apart was caused as the earth somehow expanded.
Please don't feel the need to debunk that theory, I'm taking it with a grain
of salt. I just want to figure out how much the earth has increased in mass
if that hypothesis is true and if the density has remained constant, but I
don't know how.