There are 8 fluid ounces in 1 cup. You can solve this problem using these proportions:

It states that there are 8 fluid ounces in every 1 cup and 144 fluid ounces in every
x cups. We have to solve for
x using cross-multiplication:

Vickie can fill 18 1 cup candle molds with 144 fluid ounces of scented candle wax.