Prata chapter 7 exs 8

//prata exc 7 chapter 7
//working, but i'm not happy about names vars and consts
//have to read a book about properly naming!
//another matter - which is better style -introducing after_tax or not?
#include <stdio.h>
#include <ctype.h>
#define O_RATE 1.5 //overtime rate
#define TAX1 0.15
#define TAX2 0.2
#define TAX3 0.25
#define BREAK1 300.0
#define BREAK2 450.0
#define WEEK 40.0

int main()
{
    float hours,before_tax, after_tax, tax,h_rate;
    int t, flag = 1;
    printf("How many hours have you worked this week?\n");
    scanf("%f",&hours);
    while(flag)
    {

        printf("Choose your hourly tariff: 1. 8.50/h 2. 9.50/h "
            "3. 10.00/h 4. 11.00/h 5. 22.00/h\n");
        scanf("%d",&t);
        flag = 0;
        switch(t)
        {
            //flag=0;
        case 1:
            h_rate = 8.50;
            break;
        case 2:
            h_rate = 9.50;
            break;
        case 3:
            h_rate = 10.00;
            break;
        case 4:
            h_rate = 11.00;
            break;
        case 5:
            h_rate = 22.00;
            break;
        default:
            flag = 1;
        }
    }
    printf("you chosen hourly rate of %f\n",h_rate);

    //calculating salary before tax
    if(hours<=WEEK)
        before_tax = hours * h_rate;
    else
        before_tax = WEEK*h_rate +(hours-WEEK)*O_RATE*h_rate;

    //calculating taxes
    if(before_tax<BREAK1)
    {
        tax = before_tax*TAX1;

    }
    else if(before_tax<BREAK2)
    {
        tax = BREAK1*TAX1+ (before_tax-BREAK1)*TAX2;

    }
    else
        tax = BREAK1*TAX1 + (BREAK2-BREAK1)*TAX2+ (before_tax-BREAK2)*TAX3;

     after_tax = before_tax - tax;

     printf("before %f, after %f, tax %f",before_tax,after_tax,tax);


    return 0;
}