8 + 6 x [ 4 + 27 : ( 0 + a x 9 ) ] = 50
6 x [ 4 + 27 : ( 0 + a x 9 ) ] = 50 - 8
6 x [ 4 + 27 : ( 0 + a x 9 ) ] = 42
4 + 27 : ( 0 + a x 9 ) = 42 : 6
4 + 27 : ( 0 + a x 9 ) = 7
27 : ( 0 + a x 9 ) = 7 - 4
27 : ( 0 + a x 9 ) = 3
0 + a x 9 = 27 : 3
a x 9 = 9
a = 9 : 9
a = 1 → numarul, aflat prin metoda mersului invers
