try yourself |run program

#include <stdio.h> 
#include <conio.h> 
void main(){ 
 int a;
 int b;
 int sum;
 clrscr();
 printf("Enter value of a: ");
 scanf("%d",&a);
 printf("\n Enter value of b: ");
 scanf("%d",&b);
 sum = a + b;
 printf("\n %d + %d = %d",a,b,sum);
 getch();
}

Program Output

Enter value of a: 20
Enter value of b: 30
20 + 30 = 50