A monthly fee is charged by an internet service provider according on tier usage as follows: Data Charges Rates, in Megabit(mb) Usage(n), in Gigabit(gb) 0.0 5.0 On a piece of paper, write a C++ program that uses functions and selections to estimate the fee to be paid by a subscriber based on the quantity of data used. It should be noted that the tax rate is 6%. Define global constants for the conversion rate, tiered rates, and tax rate. Sample run: Enter the amount of data used (in gbs): 2.5 Enter * STATEMENT * Charge (data used: 2.5 gbs) £ 125.00 Таx (6%) £7.50 Total £ 132.50 The program's design MUST have the main (15 marks) and the FOUR (4) functions listed below, as well as the structural chart with data flow illustrated below: main charge ax usage charge Ausage usage V charge tax get_data get_charge get_tax print_stmt • get_data : Read input data from the keyboard • get_charge: Process the input data and return the charge • get_tax : Compute and return the tax • print stmt: Print the statement