111-3 (x-3 (x-3 (x-3))) = 3

111 - 3 * (x - 3 * (x - 3 * (x - 3))) = 3;

Раскроем скобки поэтапно в уравнении и приведем подобные значения.

111 - 3 * (x - 3 * (x - 3 * x - 3 * (-3))) = 3;

111 - 3 * (x - 3 * (x - 3 * x + 9)) = 3;

111 - 3 * (x - 3 * (-2 * x + 9)) = 3;

111 - 3 * (x - 3 * (-2 * x) - 3 * 9)) = 3;

111 - 3 * (x + 3 * 2 * x - 3 * 9) = 3;

111 - 3 * (x + 6 * x - 27) = 3;

111 - 3 * (7 * x - 27) = 3;

111 - 3 * 7 * x + 3 * 27 = 3;

111 - 21 * x + 60 + 21 = 3;

110 + 1 - 21 * x + 60 + 21 = 3;

192 - 21 * x = 3;

-21 * x = 3 - 192;

-21 * x = - 189;

x = 189/21;

x = 9.