524 : 4 +4 × {36 - 32 : 16 × [15 + ( 24 : x - 20 : 5 ) × 9 ] + 7}=183
131 + 4 × { 36 - 2 ×[ 15 + ( 24 : x - 4 ) × 9 ] + 7 } = 183
4 × { 36 - 2 × [ 15 + ( 24 : x - 4 ) × 9 ] + 7 } = 183 - 131
4 × { 36 - 2 × [ 15 + ( 24 : x - 4 ) × 9 ] + 7 } = 52
36 - 2 × [ 15 + ( 24 : x - 4 ) × 9 ] + 7 = 52 : 4
36 - 2 × [ 15 + ( 24 : x - 4 ) × 9 ] + 7 = 13
36 - 2 × [ 15 + ( 24 : x - 4 ) × 9 ] = 13 - 7 = 6
2 × [ 15 + ( 24 : x - 4 ) × 9 ] = 36 - 6
2 × [ 15 + ( 24 : x - 4 ) × 9 ] = 30
15 + ( 24 : x - 4 ) × 9 = 30 : 2
15 + ( 24 : x - 4 ) × 9 = 15
( 24 : x - 4 ) × 9 = 15 - 15
( 24 : x - 4 ) × 9 = 0
24 : x - 4 = 0 : 9 = 0
24 : x = 0 + 4 = 4
x = 24 : 4
x = 6 → numarul aflat prin metoda mersului invers
