Optimizing/reducing functions with same in/out types to combine them in a simpler function?

Disclaimer: I have almost no mathematics notions, so this question could be very basic for some of you.

I'm searching for the name of a concept which consists in combining functions together (say, functions with the same input and output types and number of parameters) to make them simpler.

Suppose I have these 3 methods with the same signature:

addOne(param: number): number {
   return param + 1;
}

addTwo(param: number): number {
    return param + 2;
}

multiplyByThree(param: number): number  {
    return param * 3;
}

Now I know that I'll always use these functions in the same order and same param.

Ex: I will process a sound or an image.

I want to avoid uselessly applying coefficient or offsets that could be computed together (optimization/regression).

Let's say I have this imaginary library with a method called computeOptimizedFunction that applies this concept to my functions. It takes any number of functions with the same signature as input.

var optimized = computeOptimizedFunction(addOne, addTwo, multiplyByThree);

Actually equals to:

var optimized = (param: number) => 3 * (param + 3);

Anyone here has an idea of how this concept or pattern is called, if it exists?