Hi all. I am fairly new to programming. I started with C since I was a EE student. I have a simple C program that needs to be improved by I don't know what else I could do.

Here's the code (I'm using VS C++ to compile)
Code:
#include "stdafx.h"

int salary = 0;
int fuel = 0;
double toll = 0;
int food = 0;
double balance = 0.00;

int calBalance(void);

int main()
{
    int workDays = 0;

    puts("My console in C to calculate my budget. Every component except salary takes DAILY use.\n");

    printf("Working Days: ");
    scanf("%d", &workDays);

    printf("Salary: ");
    scanf("%d", &salary);

    printf("Fuel: ");
    scanf("%d", &fuel);

    fuel = fuel * workDays;

    printf("Toll: ");
    scanf("%lf", &toll);

    toll = toll * workDays;

    printf("Food: ");
    scanf("%d", &food);

    food = food * workDays;

    calBalance();
    printf("\nBalance: %.2f", balance);
         
    puts("");    

    return 0;
}

int calBalance()
{
    balance = salary - (fuel + toll + food);
  
    return balance;
}
I think I don't need to explain the code since it is very straightforward. I feel like it can't be improved in the context of C(not C++).

Any suggestion?

Thanks.