Of the two rows you ought to choose the top one
48 - 3x > 10
The second row makes the bottles grow. I wish this were true, but it is not.
After x gets to 13, she has dropped down below where she does not need to shop for more bottles.
48 - 3x > 10 Add 3x to both sides.
48 > 10 + 3x Subtract 10
38 > 3x Divide by 3
12 . 66666 So she can finish the 13th bottle but when she does, she has to go out and get more.