(please make it clear step by step with calculation not just text) Question 3 Public company Stock option Price

F is employed by a public corporation. In year 1,F was granted a stock option to acquire 2,500 shares from the treasury of her employer's corporation for $8 a share. At the time of receiving the option the shares were valued at $9 per share. In year 3, F exercised the option and purchased 2,500 shares for $20,000. At the exercise date, the shares were valued at $10 per share. In year 6,F sold all the shares for $21 per share