Can't connect with outside php file. The index page (index.php) isn't connecting with the Calculations.php page.

-----------Calculations.php----------

	//calculations.php
	//declare variables
	$order_total = ;
	$tax = $total * 0.65; //WA state sales tax as of 5/03/17
	$grand_total = $order_total + $tax;
	//perform grand total calculations
	function grandTotal($price, $sides){//if ther are sides
	$grand_total = ($price + $Quantity) + ($sides * $quant);
	}//end grandTotal()

----------index.php----------

	logo
	monday - friday 10-23 | saturday 14-02
	42 village St, New York
	powered by w3.css
	x
	Burger Types
	Tomato Soup $2.50
	Chicken Salad $3.50
	Bread and Butter $1.00
	Main Courses
	Grilled Fish and Potatoes $8.50
	Italian Pizza $5.50
	Veggie Pasta $4.00
	Chicken and Potatoes $6.50
	Deluxe Burger $5.00
	Desserts
	Fruit Salad $2.50
	Ice cream $2.00
	Chocolate Cake $4.00
	Cheese $5.50
	x
	Contact
	Reserve a table, ask for today's special or just send us a message: