Five Girl Scouts are required to sell 20 boxes of Girl Scout cookies each. Each box is sold for $5.00 but costs the Girl Scouts $2.75 to purchase. Presently, the girls have sold a total of 40 boxes. How many more boxes do the girls need to sell to reach their goal? If the girls have to purchase all of the boxes of cookies in advance, how many do they need to sell before they begin making a profit? Describe your answer and give examples.