What is the T.O.P?(Continue)

Suppose that T.O.P percentage is 90%.That means if seller could provide the pruduct and buyer could not take it he should pay 90% of worth of the product.But there is still right for buyer to take it in the certain period.For example in some LNG contracts, buyer would be able to take the cargo in the evry year of 5 successive years later.Determining of period is depend on haggling power between two sides however there are also some norms for the LNG contracts.The action of taking a cargo that the buyer has paied for it before is called "Make up" in the LNG terminology.
Sometimes default is due to seeler's act.In this circumstance buyer do not oblige to pay to seller and there is also same manner when Force Majeure is happan.Now if there are 5% seller's default and also 5% FM and the worth of cargo be 100 how much does the buyer sohoud pay?
Thers are two answers for this question:
1- (100-10)%*90%=81%
2-(100)*90%-10%=80%
Which way is right?