Section: Math

26) Frank measured the amount of liquid that evaporated over a 12-day period from his container with l equaling ounces of liquid. At the end of the day two, it had lost 3 ounces. At the end of day seven, an additional 6 ounces. By the end of day 12, the container had lost one-third of what remained at the end of day seven. Which of the following represents the remaining amount of liquid in ounces in Frank's container at the end of day 12?

1. ^l-3/₁₂
2. ^l-3/₂ - 9
3. I-(^l-9/₃)
4. ¹/₃ l-12

If l is the ounces of liquid and we're wanting to know how much was lost at the end of day 12, then we must start with what was lost at the end of day 7 (the 3 ounces from day 2+the 6 ounces from day 7 for a total of 9 ounces lost). So we have l-9, but we also know that at the end of day 12, the remaining amount is reduced by one-third of that total remaining. So divide l-9 by 3, and we subtract this amount from the total number of ounces. Answer 3 is the only correct choice.