Extra is related to Salt. Salt is related to White. White is a synonym of Fair. you are likely to find Sheep in/at/on Fair. 
Passenger is related to Bus. Bus is the opposite of Car. 
Extra <--RelatedTo--> Salt <--RelatedTo--> White <--Synonym--> Fair <--AtLocation-- Sheep 
Passenger <--RelatedTo--> Bus <--Antonym--> Car 