括号39×63÷23括号除以括号13×21÷69括号等于27
(39x63÷23)÷(13x21÷69)=(39÷13)x(63÷21)x(69÷23)=3x3x3=27
(39*63/23)/(13*21/69)=(3*13*3*21/23)/(13*21/(3*23))=(3*13*3*21*3*23)/(23*13*21)=3*3*3=27
最后等于27
