Sales Price of Trade In and Expense of Sale understanding

[javatax14]

I have situation where I traded in 2 cars in on December 27, 2023 for another car. Both cars were not paid for both still had loan balances . Car one Trade in was $26,000  Principle Owed or payoff amount was $27,238

Car Two Car two Trade in 13, 355 Principle Owed or payoff $13,410.  Both cars were used for Business.

I assume I have to multiply Car one amount by Business use pct to get amount same with car two .

Right? Also on Expense of Sale what is included in this amount? Also Car one was upside down i.e. I owed more than what car was worth. Does this matter or fact a car is traded in and there is still a balance owed on it? I have additional questions and have phone call scheduled with Tax Expert. as this whole section is confusing.

[javatax14]

If that's the case if car Trade in Value is 14,000 and payoff is $17,000 the $17,000 doesn't matter? so the gain is 14,000