On Thursday, May 14, Jack received the following letter from Cynthia:

Dear Jack, I will let you have my `Cynthia House' for this June-through-

August season, same terms under which you occupied it last year.

Please reply in a week."

Jack notice Cynthia's letter was postmarked May 11.

On May 17, Jack learned that Cynthia had sold Cynthia House to Jones for Jones' immediate occupancy.

Jack immediately wrote Cynthia,

"I'll take Cynthia House per your letter of the 11th."

The normal course of post between Jack and Cynthia and Jack and Cliff was one day.

Was a contract formed between Cynthia and Jack? Please explain.