Question

The average of the test scores of a class of p students is 70, and the average of the test scores of a class of n students is 92. When the scores of both classes are combined, the average score is 86. What is the value of p/n?

the total for the first class is 70p and the total for the second class is 92n
so the combined total is 70p+92n

but we are also told that the average score for both classes is 86
i.e. 86(p+n)

so 70p+92n = 86(p+n)
70p+92n=86p+86n
-16p=-6n
16p=6n
then p/n=6/16
p/n = 3/8