Sally’s job was particularly demanding one year, so she could not drive her daughter around to sell Girl Scout cookies. Consequently, Sally decided to buy the bulk of the cookies her daughter needed to sell and put them in the freezer to eat during the year. Sally bought 85% of the boxes of cookies that her daughter was assigned to sell. If Sally bought 51 boxes of cookies, then how many boxes of cookies did her daughter has left to sell in order to sell all of the boxes of cookies she was assigned? Please try to explain how to solve this, thank you