Answer:
Option A is the correct choice.
Step-by-step explanation:
We have been given the system of linear equations written by Draco. We are asked to find Draco's error.
Let us form a system of equations using our given information.
Let m represent the price of one muffin and b represent the cost of one bagel.
We are told that in one hour a bakery sold five muffins and nine bagels for a total of $25.50. We can represent this information in an equation as:

The next hour the bakery sold three muffins and 12 bagels for a total of $28.50. We can represent this information in an equation as:

Now let us see system of equations written by Draco.


We can see that Draco has set the price of 5 muffins and 9 bagels equal to $28.50, which is the price of 3 muffins and 12 bagels.
Therefore, Draco should have set the first equation equal to 25.50 and the second equation equal to 28.50. The correct choice is option A.