Math operations with loop & merge field data (or embedded data)

Hi,
I want to perform maths operations with loop and merge field data. For simple arithmetic, I can write say: $e{ ${lm://Field/2}+3}. But I want, say, the maximum of loop and merge field and an embedded data field:
max(${lm://Field/2}, $e{ e://Field/word + 3 }). How do I implement something like this? I am not good at Javascript, so if it requires custom code could you please provide the code as well? Thanks in advance!