Which relation is a function of x?

Mrs. blake's bill at a restaurant is $42.75. she wants to leave the waiter an 18% tip. how much will she pay in all, including the tip?

Abook store is having a 30 perscent off sale. diary of the wimpy kid books are now 6.30 dollars each what was the original price of the books

Ze trinomial x2 + bx – c has factors of (x + m)(x – n), where m, n, and b are positive. what is ze relationship between the values of m and n? explain how you got ze answer