Question

kamini says,rajeev's grandfather is the inly son of my father.how is kamini related to the man?

Answer 1

as your question says that :-

kamini says that rajeev's grandfather is the only son of my father .
it means kamini is rajeev's grandfather's sister .
or , we can say that she is also the grandma of rajeev

Answer 2

only son of kamini's father = kamini's only brother
ie rajeev's grandfather =only brother .
So kamini is the grandmother of rajeev.

HOPE THE ANSWER HELPS YOU