ช่วยคิดโปรแกรมคิดค่าโทรศัพท์ เขียนเเบบ Java หน่อยนะค่ะ ไม่รู้ว่าต้องทำยังไงจริงๆค่ะ

public class TelBoard {
	
	public Double TelBoards(Double firstTime, Double lastTime){
		
		Double totalFirstTime = 0.00;
		
		if((firstTime >= 6.01 && firstTime < 18.00) && (lastTime > 06.01 && lastTime <= 18.00)){
			totalFirstTime = 12*60*3.0; // 12 Hour
		}else if((firstTime >= 18.01 && firstTime < 22.00) && (lastTime > 18.01 && lastTime <= 22.00)){
			totalFirstTime = 4*60*1.5; // 4 Hour
		}else if((firstTime >= 22.01 && firstTime < 24.00) && (lastTime >= 0.00 && lastTime <= 06.00)){
			totalFirstTime = 8*60*1.0; // 8 Hour
		}else{
			
		}
		return totalFirstTime;
	}	
}

import java.util.Scanner;


public class telBetweenTime {
	
	public static void main(String[] args){
		
		Scanner scanner = new Scanner(System.in);
		System.out.println(">>>>>>>>>>>>> Welcome to Tel <<<<<<<<<<<<");
		System.out.print("Please enter the FirstTime: ");
		double firstTime = scanner.nextDouble();
		
		System.out.print("Please enter the LastTime: ");
		double lastTime = scanner.nextDouble();
		
			TelBoard tel = new TelBoard();
			Double priceTotals = tel.TelBoards(firstTime, lastTime);
			if(priceTotals == 0.0){
				System.out.print("Time is not parttime !!");
			}else{
				System.out.print("Time: "+firstTime+"-"+lastTime+" TotalPrice: "+priceTotals+ " Baht");
			}
			
	}
	
}