We convert both 2/3 and 1/6 into a similar fraction. In this case, the simplest way to answer the problem is to convert them into eighteenths, as when we convert them to this, the numberator will show the amount of ounces used. SO, 2/3=12/18=12 ounces used and 1/6=3/18=3 ounces used. The total answer of ounces used is 15, so 18-15=3 ounces left
