To combine the numerical parts of the expression, we can perform the addition:

1. Start by adding \(72.121\) and \(27.121\):
\[
72.121 + 27.121 = 99.242
\]

2. Then, add \(121\):
\[
99.242 + 121 = 220.242
\]

So, the combined result for the first part is:
\[
220.242 + 121a
\]

Thus, if we combine both parts of your expression, the final result is:
\[
220.242 + 121a
\]