Răspuns:
126-[(126:6+109)x75:25+21:3)]:10
=126-[(21+109)x75:25+21:3)]:10
=126-(130x75:25+21:3):10
=126-(9750:25+21:3):10
=126-(390+21:3):10
=126-(390+7):10
=126-397:10
=126-39 rest 7
=80