Ответ:

  1. \(52\,735+11\,665=64\,400\); \(64\,400-57\,327=7\,073\).
  2. \(42\,731-15\,931=26\,800\); \(26\,800-16\,572=10\,228\).
  3. \(5\,269-4\,887+1\,609=1\,991\); \(18\,001-17\,993=8\); \(1\,991-8+2\,319=4\,302\).

Ответ: 1) 7 073; 2) 10 228; 3) 4 302.