Create a script that calculates the amount of tip a customer should pay, based on the number of customers and the amount of the bill. Create an HTML document containing a form with two text boxes one for the number of customers, and the other for the amount of the bill (without tax and gratuity). Compute any tables with 6 or more customers with 18% gratuity, and tables with 5 or less with 15% gratuity. Use the appropriate decision structure to create the program. Print the gratuity amount to the screen. Save the document as bill.html and bill.php. EXTRA CREDIT (5 points): Calculate how much sales tax the customer would pay for the amount of the bill. Sales tax in NY State is 8.75%. Four amounts should be displayed for the bill: the original amount, the sales tax amount, the gratuity amount, and the total of the bill including the tax and gratuity amounts.