Code:
#include<stdio.h>
#include<stdlib.h>
main() {
int grade = 0, sum = 0, pass = 0, percent, fail = 0;
while (grade != -1) {
printf("Enter a numeric grade (-1 to quit):");
scanf_s("%i", &grade);
if (grade >= 70 && grade <= 100)
pass = pass + 1;
if (grade > 100)
printf("This is not a valid grade.\n");
if (grade > 0)
sum = sum + 1;
if (grade < 70 || grade > 100)
fail = fail + 1;
}
printf("You entered %i passing grades.\n", pass);
percent = fail / sum * 100;
printf("%i%% of the valid grades entered are passing grades.\n", &percent);
system("pause");
}