9+х=14;
х = 14 - 9
х = 5
проверка: 9 + 5 = 14, 14 = 14
...................................................................................................
7-х=2;
7 - 2 = х
х = 5
проверка: 7 - 5 = 2, 2 = 2
..............................................................................................
х-1=0;
х = 1
проверка: 1 - 1 = 0, 0 = 0
..............................................................................................
х+5=6
х = 6 - 5
х = 1
проверка: 1 + 5 = 6, 6 = 6