Sequence Analysis:
To find the next term in the sequence 7G, 11K, 13M, we need to analyze the pattern and identify the underlying rule governing the sequence. Let's break it down step by step.

Step 1: Analyzing the Numbers:
Looking at the numbers in the sequence (7, 11, 13), we can observe that they are increasing by 4 and 2, respectively.

Step 2: Analyzing the Letters:
Now let's focus on the letters in the sequence (G, K, M). We can notice that they are corresponding to the positions of the numbers in the English alphabet (7th, 11th, 13th letters).

Step 3: Combining the Numbers and Letters:
By combining the information from steps 1 and 2, we can conclude that the numbers represent an arithmetic progression with a common difference of 4 and 2, respectively, and the letters correspond to the positions of the numbers in the English alphabet.

Step 4: Finding the Next Term:
To find the next term in the sequence, we need to apply the same pattern. The next number should be 15, obtained by adding 2 to the previous number (13). The next letter should correspond to the 15th letter in the English alphabet, which is O.

Final Answer:
Therefore, the next term in the sequence is 15O.

Summary:
In summary, the given sequence follows a pattern where the numbers increase by 4 and 2 successively, and the letters correspond to the positions of the numbers in the English alphabet. By applying this pattern, we determined that the next term is 15O.