We will use unitary method here.
Number of vases Lexi needs to buy =105
Number of vases in one package =6
So in order to find how many package she needs to buy , we divide number of vases by number of vases in one package.
Number of packages Lexi needs to buy =105/6 = 17.5
Rounding off 17.5 we have 18.
Answer: Lexi needs to buy 18 packages.