CubeCart v5.2.0 | Pricing Calculator.

HI ALL, I AM VERY KEEN TO GET A PROJECT SORTED ON MY DOMAIN FOR A CUSTOMER [login to view URL] I NEED A CALCULATOR MADE SO THE SYSTEM AUTOMATICALLY WORKS OUT THE COST OF THE ROLL OF ARTIFICIAL GRASS BASED ON THE SELECTIONS MADE IN THE PRODUCT OPTIONS. BASICALLY I NEED TO TIMES PRODUCT OPTION (WIDTH) BY PRODUCT OPTION (LENGTH) TO GIVE ME THE PRICING FOR THE PRICE OF THE AREA... JUST LIKE PRICING UP A CUT OF CARPET. I ALSO WANT IT TO SHOW THE COST BELOW SO THE CUSTOMER CAN SEE THE PRICE BEFORE PROCEEDING TO CHECKOUT. I HOPE THIS MAKES SENSE AND WILL LOOK FORWARD TO YOUR REPLY'S. THANK YOU IN ADVANCE.