1) I'm a little puzzled by the description. Are these "stock AAA" the same stock? In other words, did your first 120,000 increase in value by the time you purchased the 57,000?
2) You seem to have Share / Dollar, rather than the intended Dollar / Share.
3) Just keep the same proportions.
100,000 * (120,000)/(257,000) = 46,693