Brooks and his friend Chris decided to purchase a motorhome together. They specifically wanted a motorhome with two air conditioning units located on the roof. When the motorhome arrived, there was only one rooftop air conditioner. The seller, World RV Sales offered to fix the motorhome by putting on the second unit, but there would be a hole in the roof. Brooks and Chris rejected this solution. Brooks and Chris initially made a $5,000 deposit on the motorhome with the remainder of $45,000 to be paid upon delivery. Could World RV's offer be considered a "conforming delivery" or "substitute" which Brooks and Chris would have to accept? Discuss the issues involved.