There are six cases in which the car, key and goat can be randomly organized.
(C car, G goat, K key)
C G K
C K G
K G C
K C G
G C K
G K C
The strategy could be they would use is that Art would choose Doors 1 and 2, while Ann will choose Doors 3 and 2. why?
2/3 cases have C on the left or in the middle.
2/3 cases have K on the right or in the middle
1/2 cases have C on the left or in the middle AND K on the right or the middle... hmm.