Edwina bought a chargeable asset in August 2010 for £240,000, paying acquisition costs of £12,000. In June 2017 she sold a one-quarter interest in the asset for £100,000 and incurred disposal costs of £5,000. The remaining three-quarters interest in the asset was valued at £500,000 in June 2017. 

(a) Compute the chargeable gain arising in June 2017. 

(b) Also compute the chargeable gain arising in January 2022, when Edwina sold her remaining three-quarters interest in the asset for £520,000. Assume that disposal costs in January 2022 were £nil.