Linux Bash script, how to use the output from a line within the next line?

I am writing a bash script that needs to take the output from one line and use that within the next line, I am wondering if there is a way to do this, the example

1st line: return data
2nd line (output from "return data"): data1
3rd line: perform action on "data1"

I hope my example is clear.. so basically the I am wondering how could I automatically grab the output from the second line and then use that value within the 3rd line?