Please Help Calling function

[AlanGRutter]

if the value of z is more than twice the value of first return z; otherwise , return 2 times first minus z.

This is different to what you originally posted and is why I couldn't make any sense of the statement you did provide. It is still ambiguous

2 times first minus z

is that

(2 * first) - z

or

2 * (first -z)


Given the nature of the check to see if z > 2 * first, I suspect it is the former, since this prevents the result from being negative.

This makes function two read as

double FunctionTwo(int x, double a)
{
    double z;

    cin >> z;
    z += a;

    int first = FunctionOne(6,8);
    first += x;

    return (z > (2*first)) ? z : (2*first) - z;
}

I also note you haven't modified your one and two functions as I posted earlier for you. If you want to pass your assignment with a decent grade, then use the stuff I posted, which is better coding.

Regards
Alan