Why callback function showing “Undefined” result?

I have been learning javascript test scripts in Postman.Here I am just learning about callback functions and I wanted to check return value is showing in the last line of print statement but the result shows ‘undefined’. Below is the code:

function add(a,b)
{
    console.log(a+b);
    return a+b;
}
function test(testname,callbackfunction,m,n)
{
    console.log(testname);
    callbackfunction(m,n);
}
console.log
(test("THis is addition",add,12,12));

Console shows:

THis is addition
24
undefined

Why it showing undefined in the last line instead of showing 24 the return value?
Thanks in advance.

I tried to store the return value in a variable but it showing the same ‘unfined’ result.

let stu=test("THis is addition",add,12,12);