quiz question on Scanner and calculations and if conditional statement

import java.util.Scanner;

public class testtt {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in=new Scanner(System.in);
		System.out.println("enter the total weight of goods you need to transport:");
		double totalWeight=in.nextDouble();
		double containers_count=Math.ceil(totalWeight/20);
		System.out.println("we need "+Math.round(containers_count)+" containers");
		
		double needed_wagons=Math.ceil(containers_count/3);
		System.out.println("we need "+Math.round(needed_wagons)+" wagons");
		if(needed_wagons<3)
		{
		System.out.println("The Quantity is too small. Sorry we can’t transport it");
		}
		else {
		double needed_trains=Math.ceil(needed_wagons/15);
		System.out.println("we need "+Math.round(needed_trains)+" trains");
		
		double x=needed_wagons/15;
		double y=needed_trains-x;
		int num_of_wagons_in_last_train=15-(int)Math.floor(15*y);
		System.out.println("we need "+num_of_wagons_in_last_train+" wagons in the last train");
		
	
		double d= (double)totalWeight/20;
		d=containers_count-d;
		int filling_ratio_of_last_container=100-(int)(d*100);
		System.out.println("filling ratio (percentage of used capacity) of the last container: "+filling_ratio_of_last_container+"%");
		}
	}
}