2.2 step tariff

In order to encourage residents to save electricity , Executed by a power company “ Step Tariff ”, The electricity price of residential users who install one household one meter is divided into two “ ladder ”： Monthly electricity consumption 50 KWH （ contain 50 KWH ） Inside , The electricity price is 0.53 element / KWH ; exceed 50 Kilowatt hour , Excess power consumption , Price hike 0.05 element / KWH . Please write a program to calculate the electricity charge .‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‪‬‪‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‭‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‮‬

Input format :

Enter the monthly electricity consumption of a user in one line （ Company ： KWH ）, Be careful ： Electricity consumption is not necessarily an integer .‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‪‬‪‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‭‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‮‬

Output format :

Output the electricity charge that the user should pay in one line （ element ）, Two decimal places are reserved for the result , The format is as follows ：“cost = Value of electricity charges payable ”; If the power consumption is less than 0, The output "Invalid Value!".‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‪‬‪‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‭‬‫‬‪‬‪‬‪‬‪‬‪‬‮‬‫‬‮‬

sample input 1:

10

sample output 1:

cost = 5.30

sample input 2:

100

sample output 2:

cost = 55.50

  Code ：

#include <stdio.h>
int main(void)
{
	double x,cost;
	scanf("%lf", &x);
	if(x>50)
    {
		cost=50*0.53+(x-50)*0.58;
		printf("cost = %.2f", cost);
	}
	else if(x>0&&x<=50)
    {
		cost=0.53*x;
		printf("cost = %.2f", cost);
	}
	else
		printf("Invalid Value!\n");
	return 0;
 }