Because these words are all translated with the subject "I", they all should underlyingly have the phoneme $/$n$-/$ word initially, which is the first person singular prefix in Bukusu. Write a rule which explains why not all words have $/$n$/$ at the beginning.

Use a single underscore $(\_)$ in the environment, no spaces;

Your rule will have to refer to natural classes;

Write the natural classes in the most general way possible;

Use the symbol $$ to describe 'nothing' in the case of insertion or deletion rules, in case they are relevant. $($i$.$e$.$ X$->/$ Y$=\text{'}$X is deleted in environment Y$\text{'},->$ X $=\text{'}$X is inserted in environment Y$\text{'})$