I'm sure some would take it that way as "x" isn't commonly used in mathematical notation as a function name, the norm is to use f, g, etc. However, the notatio

I'm sure some would take it that way as "x" isn't commonly used in mathematical notation as a function name, the norm is to use f, g, etc. However, the notation is relatively clear notwithstanding. It almost has to be x as a function with an input of 3.