This seems like an SHL numeric question. First of all the retail price index and house price index for "in the capital" columns are red-herrings, you should ignore them.
The key in this question is the fact that they say in the hypothetical situation presented that only the inflation rate will affect the house price index for "outside the capital". That said, 3 times the 96' rate is 1.5*3 which is 4.5%. An increase of 4.5% on the 96' rate of 85 will give 88.825 or rounded to 2 decimal places 88.83.