Hi, Kathy. I think I can help you with this issue.
As you mentioned about "quickly" and "see the distribution", I strongly suggest that you use our powerful "Profile" function. Through this way, the data will be visualized and very easy to read.
It is quite simple. Just select the age column, then do a Map to classify ages between 20 and 30 as true and the other as false. Then you can use Profile on the newly created column to see how these two parties are distributed.