C Program to calculate sum of 3 subjects and find average

#include<stdio.h> 

#include<conio.h>

void main()

{

 int s1, s2, s3,sum,total = 300;

 float per; 

 printf("\nEnter marks of 3 subjects : ");

 scanf("%d %d %d ", &s1, &s2, &s3); 

 sum = s1 + s2 + s3 ;

printf("\nSum : %d", sum); 

 per = (sum * 100) / total;

printf("\nPercentage : %f", per);

 getch();

}