In a certain code language:
* "visit there" is written as "na pa"
* "we and they" is written as "sa ra ta"
* "visit and come" is written as "pa ra la"

How is the word "there" written in that code language?

Let's compare the statements to isolate the code for each word:
1. Compare "visit there" ("na pa") and "visit and come" ("pa ra la"):
The common word is "visit" and the common code is "pa". Therefore, $\text{"visit"}=\text{"pa"}$.
2. Now look back at the first statement "visit there" coded as "na pa":
Since $\text{"visit"}=\text{"pa"}$, the remaining word "there" must correspond to the remaining code "na".
Thus, $\text{"there"}=\text{"na"}$.