So your objective is to find a formula to give the profit from a DV from "x" amount of money in one shot, right?
What he did in the OP didn't make any sense because he added the numbers for some reason. The number that he came up with first (adding the total value in tutors after dropping from 100b to 1b) is the useful number as that it how high you should volley to in order to do a 100b DV with only 1 drop.