解:1、九分之七÷二又五分之一+十一分之五×九分之二 =(7/9)÷(11/5)+(5/11)*(2/9) =(7/9)*(5/11)+(5/11)*(2/9) =(5/11)*(7/9+2/9) =5/11 2、【十二分之十一+十八分之七+二十四分之五】×72 =(11/12)*72+(7/18)×72+(5/24)*72 =66+28+15 =109