Your little brother gets an allowance of $2 a week. Every day he looks up at you with those big brown eyes and borrows a dollar and a half from you to buy candy. At the end of the week, he pays you his allowance. How much does he still owe you?
In this case X will equal the number of days in the week which is seven. And the result, Y, will be the amount he owes you, which is a negative.