4. On 1 May 2017, Karim wrote to Bakul offering to sell his car, for RM50000. The letter expressly stated that if Bakul did not reply by 10 May 2017, he would be deemed to have accepted the offer. On 8 May 2017, Karim sent a letter to Bakul revoking his offer. However on 10 May 2017 Bakul posted a letter to Karim accepting Kaya's offer. Karim's letter of revocation reached Bakul on 11 May 2017. Bakul's letter of acceptance reached Karim on 15 May 2017. Bakul wishes to know whether there is a valid contract between him and Karim for the sale of the car.

Advise Bakul under the law of contract.