Răspuns :
Notam cu a nr necunoscut.
{[(a×11)×2+926]:2+1999}:9=309
[(a×11)×2+926]:2+1999=309×9
[(a×11)×2+926]:2+1999=2781
[(a×11)×2+926]:2=2781-1999
[(a×11)×2+926]:2=782
(a×11)×2+926=782×2
(a×11)×2+926=1564
(a×11)×2=1564-926
(a×11)×2=638
a×11=638:2
a×11=319
a=319:11
a=29
((( ax11 )x2+ 926):2 +1999):9= 309
((ax11) x2 +926):2 +1999= 309x9
((ax11)x2+926 ):2 +1999=2781
((ax11)x2 +926):2= 2781-1999
((ax11)x2+926):2= 782
(ax11)x2+926=782x2
(ax11)x2+926=1564
(ax11)x2=1564-926
(ax11)x2=638
ax11=638:2
ax11=319
a=319:11
a=29
((ax11) x2 +926):2 +1999= 309x9
((ax11)x2+926 ):2 +1999=2781
((ax11)x2 +926):2= 2781-1999
((ax11)x2+926):2= 782
(ax11)x2+926=782x2
(ax11)x2+926=1564
(ax11)x2=1564-926
(ax11)x2=638
ax11=638:2
ax11=319
a=319:11
a=29