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{10-2×[1+3:(2×a-5)×2-2]}×5+10=10
{10-2×[1+3:(2×a-5)×2-2]}×5=10-10
{10-2×[1+3:(2×a-5)×2-2]}×5=0
10-2×[1+3:(2×a-5)×2-2]=0:5
10-2×[1+3:(2×a-5)×2-2]=0
2×[1+3:(2×a-5)×2-2]=10-0
2×[1+3:(2×a-5)×2-2]=10
1+3:(2×a-5)×2-2=10:2
1+3:(2×a-5)×2-2=5
1+3:(2×a-5)×2=5+2
1+3:(2×a-5)×2=7
3:(2×a-5)×2=7-1
3:(2×a-5)×2=6
3:(2×a-5)=6:2
3:(2×a-5)=3
2×a-5=3:3
2×a-5=1
2×a=1+5
2×a=6
a=6:2
a=3

{ 10 - 2 × [ 1 + 3 : ( 2 × a - 5 ) × 2 - 2 ] } × 5 + 10 = 10

{ 10 - 2 × [ 1 + 3 : ( 2 × a - 5 ) × 2 - 2 ] } × 5 = 10 - 10

{ 10 - 2 × [ 1 + 3 : ( 2 × a - 5 ) × 2 - 2 ] } × 5 = 0

10 - 2 × [ 1 + 3 : ( 2 × a - 5 ) × 2 - 2 ] = 0 : 5

10 - 2 × [ 1 + 3 : ( 2 × a - 5 ) × 2 - 2 ] = 0

2 × [ 1 + 3 : ( 2 × a - 5 ) × 2 - 2 ] = 10

1 + 3 : ( 2 × a - 5 ) × 2 - 2 = 10 : 2

1 + 3 : ( 2 × a - 5 ) × 2 - 2 = 5

1 + 3 : ( 2 × a - 5 ) × 2 = 5 + 2

1 + 3 : ( 2 × a - 5 ) × 2 = 7

3 : ( 2 × a - 5 ) × 2 = 7 - 1

3 : ( 2 × a - 5 ) × 2 = 6

3 : ( 2 × a - 5 ) = 6 : 2

3 : ( 2 × a - 5 ) = 3

2 × a - 5 = 3 : 3

2 × a - 5 = 1

2 × a = 1 + 5

2 × a = 6

a = 6 : 2

a = 3 → numarul, aflat prin metoda mersului invers