Retirement of partnership

Hi Sir,

can you please explain how to solve this question

4 Morris, Sally and Bernard have been partners for many years sharing profits and losses
30:50:20 respectively. On 28 February 2015 Morris retired.
Tax adjusted profits for the years ended 30 June 2014 and 30 June 2015 were
£108,000 and £120,000 respectively.
Morris has unused overlap profits of £10,000.
What is the trading profit assessable on Morris for 2014/15?
A £46,400
B £24,000
C £24,000
D £56,400

thanks