Răspuns :
128:64+(47+10-x:28+100:2:5):8=10
128:64+(47+10-x:28+10):8=10
2+(57-x:28+10):8=10
2 +[(57×28-X+280):28]:8=10
2+(1876-X):28:8=10
2 + (1976-X):224=10
2 × 224+(1876 -X ) =10 × 224
448 + 1876 - X = 2240
2324 - X = 2240
2324 - 2240 =X
X=84
128:64+(47+10-x:28+10):8=10
2+(57-x:28+10):8=10
2 +[(57×28-X+280):28]:8=10
2+(1876-X):28:8=10
2 + (1976-X):224=10
2 × 224+(1876 -X ) =10 × 224
448 + 1876 - X = 2240
2324 - X = 2240
2324 - 2240 =X
X=84
128 : 64 + (47 + 10 - x : 28 + 100 : 2 : 5 ) : 8 = 10
2 + ( 57 - x : 28 + 10 ) : 8 = 10
( 57 - x : 28 + 10 ) : 8 = 10 - 2
( 57 - x : 28 + 10 ) : 8 = 8
57 - x : 28 + 10 = 8 × 8
57 - x : 28 + 10 = 64
57 - x : 28 = 64 - 10
57 - x : 28 = 54
x : 28 = 57 - 54
x : 28 = 3
x = 3 × 28
x = 84 → numarul, aflat prin metoda mersului invers
2 + ( 57 - x : 28 + 10 ) : 8 = 10
( 57 - x : 28 + 10 ) : 8 = 10 - 2
( 57 - x : 28 + 10 ) : 8 = 8
57 - x : 28 + 10 = 8 × 8
57 - x : 28 + 10 = 64
57 - x : 28 = 64 - 10
57 - x : 28 = 54
x : 28 = 57 - 54
x : 28 = 3
x = 3 × 28
x = 84 → numarul, aflat prin metoda mersului invers