The loss price of the first price reduction = 2.5x * (1-30%) =1.75x.
Bankruptcy price of the second price reduction = loss price * (1-30%) =1.75x * 0.7 =1.225x.
Third price reduction = bankruptcy price * (1-30%) =1.225x * 0.7 = 0.8575x.
Required percentage = fire price/original price =0.8575X/X=85.75%.