somebody please help me to correct this coding program
#include <stdio.h>
void readmarks (int* num1,int* num2,int* num3);
void grademarks (int num1,int num2,int num3,int* num4,int* num5,char* grade);
void printmarks(char grade);
int main ( void)
{
int num1;
int num2;
int num3;
int num4;
int num5;
char grade;
readmarks (&num1,&num2,&num3);
grademarks (num1,num2,num3,&num4,&num5,&grade);
printmarks (grade);
return 0;
}
void readmarks (int* num1,int* num2,int* num3)
{
printf("Please enter your 1st test mark:\n");
scanf ("%d",num1);
if(*num1>100)
printf("\aError\n");
printf("Please enter your 2nd test mark:\n");
scanf("%d",num2);
if (*num2>100)
printf("\aError\n");
printf("Please enter your 3rd test mark:\n");
scanf("%d",num3);
if (*num3>100)
printf("\aError\n");
return ;
}
void grademarks (int num1,int num2,int num3,int* num4,int* num5,char* grade)
{
*num4=(num1+num2+num3)/3;
*num5=(num3+num2)/2;
if(*num4>=90)
*grade='A';
if(*num4>=70,*num4<90)
if(num3>90)
*grade='A';
else
*grade='B';
if(*num4>=50,*num4<=70)
if(*num5>70)
*grade='C';
else
*grade='D';
if(*num4<50)
*grade='F';
return ;
}
void printmarks(char grade)
{
printf("your grade is %c\n",grade);
return;
}