Melanie bought a house on 1 September 1990 for £31,000. The house was sold on 31 December 2021 for £173,000. Compute the chargeable gain arising in each of the following cases: 

(a) Melanie occupied the house as her principal private residence throughout the entire period of ownership. 

(b) Melanie occupied the house throughout her period of ownership with the exception of the period between 1 June 1997 and 31 May 2001 when she lived with a friend. During this time the house stood empty. 

(c) As (b) except that the house was let as residential accommodation during Melanie's absence.