James bought 5 boxes of cookies and 2 cakes at the store for his party. the cakes cost $4 each and his total bill was $28.50, how much was each box of cookies?

Number of cookie boxes bought by James = 5
Number of cakes bought by James = 2
Cost of each cakes = $4
Total bill paid by James = $28.50
Let us assume the cost of the each boxes of cookies = x
Then
5x + (2 * 4) = 28.50
5x + 8 = 28.50
5x = 28.50 - 8
5x = 20.50
x = 20.50/5
   = 4.10
So we can see from the above deduction that the cost of each boxes of cookies bought by James is $4.10