Basically, you just divide 0.59 by 15 so you can find how much it costs per ounce and you round to the nearest tenth of a cent.
Therefore, 0.59 ÷ 15 ≈ 0.039 (actually 0.393 recurring but it says to round to the nearest tenth of a cent)
This means that one ounce of store-brand tomato sauce costs about $0.039.
