.. In a certain examination, the average grade of all students in class A is 68.4 and stu- dents in class B is 71.2 . If the average of both classes combined is 70, find the ratio of the number of...

Extracted text: .. In a certain examination, the average grade of all students in class A is 68.4 and stu- dents in class B is 71.2 . If the average of both classes combined is 70, find the ratio of the number of students in class A to the number in class B.