Hi there brittanielane, welcome to the forum.
Let's look at the problem as follows, you have 2 items and each need preparation and baking.
Let's call the numbers (loaves) of bread = B and the number of muffins made = M
Now for preparation and baking you need to come up with a separate equation in terms of B and M. These will be your contraints.
Here's a hint.
The objective function in this case will maximise profit, let's call that P, is also in terms of B and M.