Times Mirror Co. said it has agreed...

Times Mirror Co. said it has agreed to swap several cable TV systems with a partnership of United Artists Communications and Tele-Communications. Neither Times Mirror, which publishes the Los Angeles Times, nor the partnership put a value on the deal. But analysts estimated that it would be worth about $740 million, based on an average price of $2,000 per subscriber. The companies had announced tentative plans for the exchange in early October, but the details were not worked out until now, Times Mirror said. The partnership will get cable systems serving about 185,000 customers in Phoenix and other Arizona communities, while Times Mirror will receive systems with a similar number of subscribers in Massachusetts, New York, Illinois, Ohio, Nevada and South Lake Tahoe, Calif. Times Mirror also agreed to acquire the Rock Island, Ill., cable system of Tele-Communications for an undisclosed price.