Final answer:
The price of a muffin at the bake sale is $3.75.
Step-by-step explanation:
To find the price of a muffin at the bake sale, we first need to calculate the total cost per muffin. Lee spends $1.25 on ingredients for each muffin. He charges customers 300% of the amount it costs him to make them, so the price of a muffin is 3 times the cost of making it.
Therefore, the price of a muffin at the bake sale is $1.25 x 3 = $3.75.