3. Develop a class Customer which contains data member: customerName, phone, balance, simType, and internetBalance. Implement necessary methods to set the value of each variables. Now design another class called offer that contains a function calculateOffer () which takes an object of class customer as a parameter and provides offer to the customer depending on the following criteria: i. If the customer is Robi user add 50MB to his internetBalance ii. If the customer is Airtel user provides 10% cash on his balance