If Function

New to programming and I'm my best to understand, the book is little to no help.
Write a program that asks the user to enter five test scores. The program should display a letter grade for each score and the average test score. Design the following functions in the program:

determineGradeâ€”This function should accept a test score as an argument and return a letter grade for the score (as a String), based on the following grading scale:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
//Declare Integer test1, test2, test3, test4, test5
//Declare String score1, score2, score3, score4, score5
//Declare Integer average

cin >> Test1
cin>> test2
cin>> test3
cin>> test4
cin>> test5
 ``12345678910111213141516171819202122232425262728`` ``````#include using namespace std; int main() { int Score[5]; for (int i = 0; i < 5; ++i) { printf("Enter Score %d: ", i); cin >> Score[i]; } for (int i = 0; i < 5; ++i) { if (Score[i] >= 90) printf("Grade %d: A\n", i); if (Score[i] >= 80 && Score[i] < 90) printf("Grade %d: B\n", i); if (Score[i] >= 76 && Score[i] < 80) printf("Grade %d: C\n", i); if (Score[i] >= 70 && Score[i] <= 75) printf("Grade %d: D\n", i); if (Score[i] < 70) printf("Grade %d: F\n", i); } system("pause"); return 0; }``````