1 способ. Решить поэтапно.
(1 2/3 * х + 6 5/42) : 2 3/4 = 3 1/11
1 2/3 * х + 6 5/42 = 3 1/11 * 2 3/4
1 2/3 * х + 6 5/42 = 34/11 * 11/4
1 2/3 * х + 257/42 = 17/2
1 2/3 * х = 17/2 - 257/42
1 2/3 * х = (357-257)/42
1 2/3 * х = 50/21
х = 50/21 : 5/3 = 50/21 * 3/5 = 10/7
х = 1 3/7
2 способ. Раскрыть скобки.
( 1 2/3 * х + 6 5/42 ) : 2 3/4 = 3 1/11
1 2/3 * х : 2 3/4 + 6 5/42 : 2 3/4 = 3 1/11
5/3 * 4/11 * х + 257/42 * 4/11 = 3 1/11
20/33 * х + 514/231 = 34/11
20/33 * х = 34/11 - 514/231
20/33 * х = (714 - 514) / 231
х = 200/231 : 20/33 = 200/231 * 33/20 = 10/7
х= 1 3/7