1. (3000 - (520 + х) + (352 + 169)) - 279 = 1000; 3000 - 520 - х + 521 = 1000 + 279; 3001 - х = 1279; х = 3001 - 1279; х = 1722. 2. ((171 - 9х) : 15 + 174) : 45 = 4; (171 - 9х) : 15 + 174 = 45 * 4; (171 - 9х) : 15 + 174 = 180; (171 - 9х) : 15 = 180 - 174; (171 - 9х) : 15 = 6; 171 - 9х = 6 * 15; 171 - 9х = 90; 9х = 171 - 90; 9х = 81; х = 81 : 9; х = 9. Ответ: 1. 1722; 2. 9.