Here I write a mixed code (additional & subtraction) both. Where I use 4 variable that is for integer number. If anyone wants to use floating point number or double number. Then just write float a,b,c,d,sum. then write your code and use %f  for taking your floating or double number. You can also use more variable that you want. If you have to need more variable then you have to use array[ ]. That is different.


#include<stdio.h>
int main()

{
    int a,b,c,d,mix;

    printf("Please enter your 1st value: ");
    scanf("%d",&a);
    printf("Please enter your 2nd value: ");
    scanf("%d",&b);
    printf("Please enter your 3rd value: ");
    scanf("%d",&c);
    printf("Please enter your 4th value: ");
    scanf("%d",&d);

    mix=a+b-c+d;
    printf("\nYour total number is: %d\n",mix);


    return 0;


}

[N.T: Please notice that I just change the sign of (+) or (-) and same code as addition and subtraction . ]

Output of above code.