You need first to know how many square feet can each 7-pound bag cover.
[tex]7p*150ft^2=1050ft^2[/tex] covered by each 7p bag.
Then you need to know how many bags will he need to use to cover all the given area; [tex]\frac{2500ft^2}{1050bft^2} =2.4bag [/tex] which means 3 bags, as he cannot buy 2.4 bags!
Now you have how many bags needed, you have to multiply the number of bags by the price of one of them.
3*15.98=47.94$
Please note, the question may also treat 2.4 as a valid option, if so, then the total price will be 2.4*15.98=38.1$
Hope this helps!
