Answer:
LMELMELME
Explanation:
The letters 'N' and 'R' are the third and sixth letters of the word 'Denver'.
*Think, every third letter of the word.
The word 'Baltimore' has a number of letters also divisible by 3 ('Baltimore' contains 9, 'Denver' contains 6), so the rule established above will also work here.
Underlining every third letter in 'Ba<u>l</u>ti<u>m</u>or<u>e</u>', we get the first part of the pattern, '<u>LME</u>'.
In the secret code language, 'NR' is repeated 3 times (including the first) to write 'NRNRNR', so by repeating every third letter of the word 'Baltimore' ('LME') three times, we get 'LMELMELME'.