How much do you earn per day calculator

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <math.h>

/*
How much do you earn per day calculator by Goran
*/

int main()
{
    float earnPerDay, day = 0, earnings = earnPerDay;
    printf("How much do you earn per day? "); // asking user how much money he earns per day.
    scanf(" %f", &earnPerDay); // gets input from user and stores it into float earnPerDay.
    printf("\n"); // prints blank space.

    do{
        printf("Day: %.0f Cash Earned: %.0f \n", day, earnings); // prints earnings for every day in month.
        day++; // increment float day by one.
        earnings += earnPerDay; // earnings float.
    }while(day <= 31); // do code while day is less or equal to 31.

    printf("\n"); // prints blank space.
    system("pause"); // pausing program after executing.
    return 0;
}