What value(s) of x in the relations below would create a set of ordered pairs that is not a function? {(2,10),(3,-8), (6,9), (x,8), (7,4)}

Arestaurant offers delivery for their pizzas. the total cost the customer pays is the price of the pizzas, plus a delivery fee. one customer pays $23 to have 2 pizzas delivered. another customer pays $59 for 6 pizzas. how many pizzas are delivered to a customer who pays $86?