51 - ( 2 660 : 76 + x ) : 23 = 28
( 35 + x ) : 23 = 51 - 28
( 35 + x ) : 23 = 23
35 + x = 23 × 23
35 + x = 529
x = 529 - 35
x = 494 → numarul, aflat prin metoda mersului invers
Verific:
51 - ( 2 660 : 76 + 494 ) : 23 = 28
= 51 - ( 35 + 494 ) : 23 =
= 51 - 529 : 23 =
= 51 - 23 =
= 28
