So we know that Amy bought some cans of paint and 5/8 of a liter of special paint additive formulated to reduce mildew. before painting her house, she used all of the additive to put 1/8 of a liter of additive in each can. So for each can she use 1/8 of a liter, and she have 5/8 of a liter, so we need to do a division to know the amount of cans

So the answer is that she bought 5 cans.