Luigi bought four pizzas for $80. Each pizza was cut into 5 pieces. How much did each piece of pizza cost, in dollars? Let's think first. Chain of thought:
4 pizzas at $80 per pizza is $80 / 4 = $20 per pizza. If there were 5 pieces per pizza, then each piece was worth $20 / 5 = $4.
Therefore, the answer is 4.