Ron paid $799.99 per laptop for three laptops and a flat rate fee for antivirus installation for a total bill of $2,529.57 at Gigahertz Computers. Jerry paid $777.16 per laptop for three laptops plus a per laptop antivirus installation fee for a total bill of $2,481.42 at TechZone Computers. What is the difference in the amounts they paid for the antivirus installation charges?