The answer would be B because the 100 stays in there and you are adding 8% per year. Hope this helps.
You could say that you spent (purchased) 85% of the money that you had.
You spent a total of $85.
If you create the fraction 85/100, that is the same as saying you spent 85% of the money.
The starting percent is 100%. After one hour, bacteria tripled, so it is 300%.
