Miller leased an apartment to Baker for $600 a month, payable the last day of each month. The term of the written lease was from January 1, 2011, through April 30, 2012. On March 15, 2011, Baker moved out, telling Miller that he did not get along with the other tenants. Miller replied, "Well, you're not the most polite person in the world; I can probably find someone far more suitable." Baker sent the apartment keys to Miller by mail. Miller wrote Baker, "It will be my pleasure to hold you for every penny you owe me. I am renting the apartment on your behalf to Charles until April 30, 2012, at $425 a month." Baker had paid his rent through February 28, 2011. Charles entered the premises on April 1, 2011. How much rent, if any, may Miller recover from Baker?