Langston, the owner of a 10-unit apartment house in City, California, leased an apartment to Tankersley, with the term beginning on January 1. Although the apartment would have been worth $3,500 a month in satisfactory condition, the parties reached an agreed rent of $2,500 a month because the apartment suffered from a severe ventilation problem. The defective ventilation forced Tankersley to keep the bathroom door shut and to run the fan continuously. Tankersley thought he could tolerate the ventilation problem in order to obtain an apartment he otherwise could not afford, but soon found the situation intolerable. The apartment constantly suffered from moisture and foul odor problems. Furthermore, the constant running of the fan led to a fire in the apartment. Tankersley started to complain to Langston about the problem within a week of moving in. Several of these complaints were in writing, and the complaints continued through June. Langston did make several attempts to correct the problem - he installed a dehumidifier, sealed the foundation, repainted some of the surfaces, etc. - but these efforts were ineffective. Complete correction would have required the installation of several new windows and a sophisticated ventilation system, all of which would cost in excess of $10,000. In April, after paying three months' rent, Tankersley stopped paying his rent and told Langston that he would not pay again until the ventilation problem was corrected. Langston responded by insisting that Tankersley had made a deal, and was bound by it. In June, after failing to receive any rent for the prior three months, Langston served notice to quit on Tankersley for failure to pay rent. He intends to start an eviction action if Tankersley does not vacate. Tankersley intends to assert his defenses and file a counterclaim against Langston if Langston proceeds with an eviction. Please discuss the rights, duties, and responsibilities of the parties. (Hint: remember the discussion we had in class)