functions

[baketballcourt]

Write the function void readTestScores (double &exam, double &tavge) that does the following:
- print the prompt: "enter exam score:" than read the exam score
- print the prmpt: "enter all test scores:" then read 7 test scores in a loop, and than computer their average
- the exam score and the average of the test scores are returned to the calling function using the reference parameters exam and tavge respectively

#include <iostream>
using namespace std;



void readTestScores(double & exam, double &tavge);
double computeFinalScore(double exam, double tavge);
char getLetterGrade(double score);
void printComment(char grade);
int main()
{
   
    double exam;  // a student's average exam score
    double tavge;  // a student's average test score
    
    /*read the student's exam scores and computer their average*/
    cout  <<  endl  << "Enter Students ID number:\t"; 
    cout  <<  endl  <<  "Enter exam score:\t";
    exam = computeFinalScore(1);
    
    /*read the student's test score and computer their average*/
    cout  << endl  <<  "Enter all test scores:\t";
    tavge = computeFinalScore (7);
    
    /*compute and print the student's average score*/
    cout  <<  endl  <<  "The average score is:\t"  <<  (.4 * tavge + .6 * exam;
    char grade;


       cout<<"\n Enter your Marks = ";
       cin>>marks;

       if(marks>=80 && marks<=100)
      grade='A';

       elseif(marks>=70 && marks<80)
      grade='B';

       elseif(marks>=60 && marks<70)
      grade='C';

       elseif(marks>=50 && marks<60)
      grade='D';

       else
      grade='F';

       cout<<"\n Your Grade is = "<<grade<<endl;

       getch( );

need help i need to add more and figure out what to do