Artificial language is given below for sentences:

'tap il pue' means Life is hard
'pue tiw il' means hard is nothing
'tap zeu ylu' means Enjoy your life

Which code could mean 'life is nothing' in that Artificial language?

tap tiw il

We have,

'tap il pue' means Life is hard
'pue tiw il' means hard is nothing
'tap zeu ylu' means Enjoy your life

So, 'is' present in both first and second sentence and the common artificial language present in both of them is 'il'

So the code for is = il

similarly the code for life from first and third sentence is tap

and we can see that we have to find the code for life is nothing.

So life word comes first and having coded as tap.

So only tap tiw il satisfies.