18.3 Edwina bought a chargeable asset in August 2006 for £240,000, paying acquisition costs of £12,000. In June 2012 she sold a one-quarter interest in the asset for £100,000, incurring disposal costs of £5,000. The remaining three-quarters interest in the asset was valued at £500,000 in June 2012.

(a) Compute the chargeable gain arising in June 2012.

(b) Also compute the chargeable gain arising in January 2017, when Edwina sold her remaining three-quarters interest in the asset for £520,000.