/sci/ - Science & Math

Hey, it's me again. Normally I wouldn't double-dip in the same /sqt/ but I'm desperate because I need to get this done so I can study for my other class' exam.
I've come on another problem, the last one I need to get done. But I'm really not sure what it is even asking.

It says to "give a recursive definition for the set of all well-formed formulas of integer arithmetic, involving integers together with the arithmetic operators +,-,*,/"
I'm not sure what exactly it is even asking me.
Does it just mean the recursive definition of each one? Or all of them together?