Răspuns: a = 9
Explicație pas cu pas:
5 + [ 16 - ( 9 : a × 8 + 7 ) ] × 6 = 2 + ( 3 × 3 )
5 + [ 16 - ( 9 : a × 8 + 7 ) ] × 6 = 2 + 9
[ 16 - ( 9 : a × 8 + 7 ) ] × 6 = 11 - 5
[ 16 - ( 9 : a × 8 + 7 ) ] × 6 = 6
16 - ( 9 : a × 8 + 7 ) = 6 : 6
16 - ( 9 : a × 8 + 7 ) = 1
9 : a × 8 + 7 = 16 - 1
9 : a × 8 + 7 = 15
9 : a × 8 = 15 - 7
9 : a × 8 = 8
9 : a = 8 : 8
9 : a = 1
a = 9 : 1
a = 9 → numarul, aflat prin metoda mersului invers