How do you calculate capital gains tax in the UK system for a painting that was bought for 150000 pound and had increased value to 330000 pounds and the person already has an income of 10000 pounds from bank interest. and also if you started a business as an art dealer before selling the painting and then sold it what would be the capital gains tax and income tax

Lower tax rate 10% or 18%

Higher tax rate 20% or 28%

Annual Exempt Amount 12,000