It would help if you showed us the values of each variable.
To me, it looks like they used an infix operator. In my opinion, this just makes it confusing.
Select "Infix Operator" from the "Evaluation" toolbar (View -> Toolbars -> Evaluation).
Three placeholders will appear. Type the first variable in the first placeholder, the function (min or max) in the second placeholder, and the second variable in the third placeholder.