Game play was more challenging than I thought. Thanks to the walk through, I could solve neither the maths puzzle nor the make a correct sandwich. I felt slight frustration and found out something was missing. First, a different symbol shall be used to represent X=52 because I simply replaced the X in the formula and summed the two numbers. Of course, I couldn't get the chest opened. Second, the jars could be labelled so that we know what the ingredients are.
Anyway, I like the ending and "Function" who was grumpy in a hilarious way.