C program to calculate Electricity Bill

/* 
	Charge Unit Condition
	For first 50 units Rs. 0.50/unit
	For next 100 units Rs. 0.75/unit
	For next 100 units Rs. 1.20/unit
	For unit above 250 Rs. 1.50/unit
	An additional surcharge of 20% is added to the bill. 
*/


#include<stdio.h>
int main()
{
	int unit;
	float amount, total_amount, surcharge;

	/* Input unit consumed from user */
	printf("Enter total Units consumed: ");
	scanf("%d",&unit);

	/* Calculate electricity bill according to given conditions */
	if(unit <= 50)
	{
		amount = unit * 0.50;
	}
	else if(unit <= 150)
	{
		amount = 25 + (unit-50)*0.75;
	}
	else if(unit <= 250)
	{
		amount = 100 + (unit-150)*1.20;
	}
	else
	{
		amount = 220 + (unit-250)*1.50;
	}

	/* Calculate total electricity bill
       after adding surcharge */
	surcharge = amount * 0.20;
	total_amount = amount + surcharge;

	printf("Your Electric city Bill = %.2f",total_amount);

	return 0;
}

Output

Enter total Units consumed: 160
Your Electric city Bill = 134.40