Step-by-step explanation:
I assume delivery fee and service fee apply only once even if I order multiple pizzas in one order.
1.
y = 12x + 2.5 + 0.75 = 12x + 3.25
2.
y = 10x + 2.5 + 0.75 = 10x + 3.25
3.
I choose : $63.25
how many large pizzas ?
63.25 = 12x + 3.25
60 = 12x
x = 5
so I can order 5 large pizzas.
how many medium pizzas?
63.25 = 10x + 3.25
60 = 10x
x = 6
so, i can order 6 medium pizzas.
FYI : if the price is actually all 3 fees for each pizza ordered, then the formulas would look like this :
large pizzas :
y = (12 + 2.5 + 0.75)x = 15.25x
and for medium pizzas:
y = (10 + 2.5 + 0.75)x = 13.25x
and you could by for $63.25
63.25 = 15.25x
x = 63.25/15.25 = 4.147540984... ≈ 4 large pizzas
and
63.25 = 13.25x
x = 63.25/13.25 = 4.773584906... ≈ 4 medium pizzas
I assume we cannot buy part pizzas.
