Răspuns:
{ 4 x [ 2 + ( 6 + a ) : 3 } - 17 } x7= 24-3
{ 4 x [ 2 + ( 6 + a ) : 3 >]- 17 } x7 =21
{ 4 x [ 2 + ( 6 + a ) : 3 ] - 17 } =21 :7
{ 4 x [ 2 + ( 6 + a ) : 3 ] - 17 } =3
4 x [ 2 + ( 6 + a ) : 3 ] - 17 =3+17
4 x [ 2 + ( 6 + a ) : 3 ] =20
[ 2 + ( 6 + a ) : 3 ] =20:4
[ 2 + ( 6 + a ) : 3 ] =5
2 + ( 6 + a ) =5x3
2 + ( 6 + a ) =15
( 6 + a ) =15-2
( 6 + a ) =13
6+a=13
a=13-6
a=7
