William wrote the expression (d + 3d) - (-d + 2) in standard form. His answer is: 4d - d + -2. Explain is error and then show the steps he should take to write the problem in standard form correctly.

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?