In a certain code language, 'ri ti gi' is written as 'Usha playing cards', 'si ni gi' is written as 'Asha playing tennis' and 'ri si wi' is written as 'cards and tennis'. What is the code for the word 'tennis' in that language?

si

The pattern here;

ri  ti  gi  =  Usha  playing  cards

si  ni  gi  =  Asha  playing  tennis

ri  si  vi  =  cards  and  tennis 

So,

Playing is coded as gi

Tennis is coded as si

Cards is coded as ri

Thus, tennis will be coded as si