We can solve this question by finding values that satisfy the given conditions.

Pam and Stanley packed several boxes with reams of paper. While both packed, Pam packed 60% of the boxes.
Let's say that, during this time, Pam and Stanley packed a TOTAL of 10 boxes.
Since Pam packed 60% of the boxes, we can conclude that Pam packed 6 boxes and Stanley packed the remaining 4 boxes

After Pam stopped, Stanley packed the same number of boxes that he had packed while working with Pam.
This means that Stanley packed another 4 boxes after Pam stopped.
So the total number of boxes that Stanley packed = 4 + 4 = 8

What is the ratio of the number of boxes Pam packed to the number of boxes Stanley packed?
Pam packed 6 boxes
Stanley packed 8 boxes

The ratio is 6 to 8
Simplify to get: 3 to 4

Answer: D

Cheers,
Brent