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

Extracted text: In a certain examination the average grade of all students in class A is 68.4 and students 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 of students in class B.