8.25+[2.85-(3又2/5-10.8×2/9)÷1又1/14]=8.25+[2.85-(3.4-2.4)÷15/14]=8.25+[2.85-14/15]=11.1-14/15=61/6（7/9-5/6+7/18）×18+3.95×6-1.45×6=14-15+7+(3.95-1.45)×6=6+2.5*6=21