Two or more independent functions (say f(x) and g(x)) can be combined to generate a new function (say g(x)) using any of the following approach.


And many more.
The approach or formula to use depends on the question.
In this case, the combined function is:

The savings function is given as

The allowance function is given as:

The new function that combined his savings and his allowances is calculated as:

Substitute values for s(x) and a(x)

Open bracket

Collect like terms


Read more about functions at:
brainly.com/question/15458447