On day 1, bid price is $20.50 and ask price is $20.70. On day 2, bid price is $20.80 and ask price is $21.00. Compute profit for buying 400 shares on day 1 and selling them on day 2 if commission is 1) $10 per transaction; 2) 0.4% of transaction value.

The correct answer is 1) $20, 2) $26.40. Can you please show me how to get to this answer using a financial calculator? Thank you