Calculate the courier charges

Write a program to accept the weight of the parcel and calculate the bill according the given price slabs.

Weight                                                Rates per Kg

<=10Kg                                                       30

Next 20 Kg                                                 20

More than 30 kg                                      15

import java.io.*;
class charges
{
    public static void main()throws IOException
    {
BufferedReaderbr=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a weight");
        double kg=Double.parseDouble(br.readLine());
        double charge=0.0;
        if(kg<=10)
        {
            charge=kg*30;
        }
        else if((kg>10)&&(kg<=30))
        {
            charge=10*30;
            charge=charge+(kg-10)*20;
        }
        else
        {
            charge=10*30;
            charge=charge+(20*20)+(kg-30)*15;
        }
System.out.println("The amount to be paid is"+charge+"Rs");
    }
}