The original amount of OJ is what we're trying to find, so that will be our variable, x. Now, keep in mind the order of events to write the correct equation. We started with the x amount of OJ, then 240 mL was taken away, to leave us with 875 mL. So, x - 240 = 875. Then we solve this by adding 240 to both sides to get the x alone. This gives us x=1,115 mL!
