Răspuns :
x = numarul
2 x - 56 = 0
2 x = 0 + 56
2 x = 56
x = 56 : 2
x = 28
Verificare : 28 x 2 - 56 = 0
2 x - 56 = 0
2 x = 0 + 56
2 x = 56
x = 56 : 2
x = 28
Verificare : 28 x 2 - 56 = 0