Thread: I Have A Questio here

Why I can't print out the change due with my coding?anyone can solve it to me?

Code:

#include<stdio.h>
#include<math.h>

void main()
{
	int discount,set_of_combo;
	double total,a_payable,amount,cash;
	double g_tax,s_tax,change_due,a_a_payable;

	printf("Enter Number Of Combo Set : ");
	scanf("%d",&set_of_combo);

	printf("Enter Discount Voucher (RM) : ");
	scanf("%d",&discount);

	//calculation
	amount = set_of_combo*7.88;
	g_tax = amount * 6 / 100;
	s_tax = amount *10 / 100;
	total = g_tax + s_tax + amount;
	a_payable = total - discount;
	a_a_payable = a_payable;
        change_due = cash - a_a_payable

	printf("Good Day and Welcome To KLFC Sdn.Bhd");

	printf("R E C E I P T\n");
	printf("+-------------------------+------------------+-------------------+\n");
	printf("+       Description       |       Rate       |     Amount(RM)    |\n");
	printf("+-------------------------+------------------+-------------------+\n");
	printf("+      COMBO SET * %d      |       7.88       |        %.2f      |\n",set_of_combo,amount);
	printf("+      Goverment Tax      |        6%%        |        %.2f       |\n",g_tax);
	printf("+      Service Tax        |        10%%       |        %.2f       |\n",s_tax);
	printf("+-------------------------+------------------+-------------------+\n");
	printf("+               S U B   T O T A L            |          %.2f    |\n",total);
	printf("+============================================+===================|\n");
	printf("+      Discount Vouvher (RM)  %.2lf                               +\n",discount);//discount voucher
	printf("+                           --------                             |\n");
	printf("+      Amount Payable         %.2lf                              |\n",a_payable);//amount payable
	printf("+                           ========                             |\n");
	printf("+      Adjusted Amount Payable                      %.2lf          |\n",a_a_payable);//adjustment amount payable
	printf("=================================================================+\n");
	printf(" CASH ");
	scanf("%.2lf",&cash);
	printf(" Change Due:\n",change_due);
	printf("==================================================================\n");
	printf("               THANK YOU and HAVE A NICE DAY\n");

}