Put everything on a common denominator first so,
we have 1/2 and 1/5, the lowest common denominator is /10
when put over 10 we have 5/10 and 2/10
now add the two together
5/10 + 2/10 = 7/10, that is how much money has been claimed by the savings account and the bubble gum total.
now subtract what has been claimed from the whole
10/10 - 7/10 = 3/10, this is the portion remaining to be spent on comic books