1﹣+= 1÷×= 0.5﹣+0.5﹣=
8.1+= (+)×24= 7××7÷=
500-213= 10÷10%= 0.25+2.83= 1.25×0.8= 3.7-3.7÷3.7=
92-33= + = × = 9÷ = ( - )×20=
一幢楼共有26层,总楼高是78米,小红家住在12楼,她家的地板离地有多高?