设计一个邮寄包裹的收费系统，在邮寄类型确定的情况下，包裹的邮资由包裹的重量a，邮寄距离b，保价金额c三个参数决定。



如：普通邮件(RegularMail)的邮费 = 3(a+b/100)+0.01c



挂号邮件(RegisterdMail)的邮费 = 4(a+b/100)+0.02c等等



请设计一个系统，计算包裹的邮资。系统使用图形用户界面，用户在图形用户界面选择邮寄类型，再输入重量、距离和报价金额，单击确定按钮系统就计算出包裹的邮资。要求系统能够灵活的增减邮寄类型和修改某种邮寄类型的邮资计算方法。-Design of a parcel of charge system, the type identified in the case of mail, parcels by the weight of the parcel postage a, mailing distance b, c insured amount three parameters. Such as: regular mail (RegularMail) postage = 3 (a+b/100)+0.01c registered mail (RegisterdMail) postage = 4 (a+b/100)+0.02c etc. Please design a system to calculate the parcel postage. System using the graphical user interface, users select the mail type graphical user interface, and then enter the weight, distance and offer amount, click the OK button the system will calculate the parcel postage. Require the system to increase or decrease mailing flexible type and modify some types of mailing postage calculation.