yazan100: Suppose that you can buy 5 apples for $2.00. How much would it cost to buy 17 apples?
Well, you would work out what 1 apple would cost first and then you would work out how much 17 cost.
Do you know how to work out how much one apple costs?
If not then I will help you more.
Let me know how you get on. If you get an answer please tell everyone on the forum what it is.