Номер 310

18 - x = 2;
x = 18 - 2;
x = 16;
18 - 16 = 2.
2 = 2;

18 : x = 2;
x = 18 : 2;
x = 9;
18 : 9 = 2;
2 = 2.

x : 2 = 9;
x = 9 • 2;
x = 18;
18 : 2 = 9;
9 = 9.

x • 9 = 81;
x = 81 : 9;
x = 9;
9 • 9 = 81;
81 = 8 1.