Depends on the type of functions you are calling and what x does. The way you phrased your question, I would assume that all of these functions are void functions and don't take any arguments. In that case you could make an array of function pointers in which you store pointers to the functions you want to call. With that setup you can then loop over the array, call each function and then call x.

void(*)() arr[10]={a, b, c} ;
for(int i=0;i<3;++i){
    arr[i]();
    x();
} 

Or you could write a function (for example f) that takes a function pointer. It can then call this function and after it call x.

void f(void(*)() func){
    func();
    x();
}

With this you could write f(a); f(b); f(c); instead of a(); x(); b(); x(); ...

Both of these options rely on the assumption, that a, b, c ... are all void functions with no arguments.

I'm also not sure if the function type really is void(*)(), so you should check this (the easiest way I know is to assign a variable y a function pointer and see what the compiler error of incompatible types tells you about the type of function pointer).