Answer: 43 brownies and 83 muffins.
Step-by-step explanation: There are 126 sweet items in total. Jalece and Kaylyn make 40 more muffins than brownies, which means that there are more muffins than brownies. Let's try 83 muffins and 43 brownies to see if it suits what we need. With 83 muffins and 43 brownies, there are 40 more muffins than brownies, so that's correct. 83 and 43 also add up to 126, which is the total that we need.
Therefore, there are 43 brownies and 83 muffins.
Let me know if this is right! :)