Average Calculation Error

I am having trouble with calculating the average of a series of grades entered. Here is my code. Any help would be appreciated.

insert

Code:

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#include<stdio.h>

float calculateAverage (float total, int items)
{
    return total / items;
}

int main(void)
{

    float classaverage, runningsum, inputnumber, high, low;

    int testamount;
    int counter = 1;

    char letter_grade;

    printf("enter amount of tests: ");
    scanf("%d", &testamount);

    printf("Enter test grade: ");
    scanf("%f", &inputnumber);
    runningsum = inputnumber;
    high = low = inputnumber;

    while (testamount > counter)
{

    printf("Enter test grade: ");
    scanf("%f", &inputnumber);

    if (inputnumber < 0)
        printf("The number you entered is negative. It will be ignored in calculations.\n");
    else if (inputnumber > 100)
        printf("The number you entered is greater than 100. It will be ignored in calculations.\n");
    else if (inputnumber < 60)
        letter_grade == 70;
    else if (inputnumber < 70)
        letter_grade == 68;
    else if (inputnumber < 80)
        letter_grade == 67;
    else if (inputnumber < 90)
        letter_grade == 66;
    else if (inputnumber <= 100)
        letter_grade == 65;


        runningsum += inputnumber;

    counter++;

}

    classaverage = calculateAverage(runningsum, testamount);

    printf("the class average is %g.\n", &classaverage);


    printf("\nhigh:\t%f\tlow:\t%f\n", high, low);


return 0;
}

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The main problem I can see is this line:

Code:

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printf("the class average is %g.\n", &classaverage);

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You want to get ride of the '&'.

I don't know if you realise this, but the variables 'high' and 'low' just contain the first in the sequence - They aren't the high and low of the list you enter.

Thank you so much! That worked.