In Mixed letter coding type of questions, three or four complete messages are given in the coded language and the code for a particular word is asked. To analyse such codes, any two messages bearing a common word are picked up. The common code word will mean that word. Proceeding smilarly by picking up all possible combinations of two, the entire message can be analysed.
If in a certain code language, 'oka peru' means 'fine cloth' ; 'meta lisa' means 'clear water' and 'dona lisa peru' means 'fine clear weather' , which word in that language means 'weather' ?
In the first and third statements, the common code word is 'peru' and the common word is 'fine'.
So, 'peru' means 'fine'.