a.On Friday 5 September, Hanna sent a email to Adam offering to buy his piano at RM3,000. The email was received by Adam at 4pm. Adam sent an email on Friday, accepting the proposal at 5pm. The email reached Hanna at 5.01pm on the same day. Meanwhile, at 4.30pm on 5 September, Hanna sent a letter to Adam withdrawing her proposal. Hanna's letter reached Adam and was read by him on 6 September. Adam sought after your advice. Advise Adam.