What is the product of the complex numbers 3-4i3−4i3, minus, 4, i and -6+i−6+iminus, 6, plus, i, where i=\sqrt{-1}i= −1 i, equals, square root of, minus, 1, end square root ?

Aarti posted a comment on her blog. each day the number of responses to her comment was 125% of the number she received on the previous day. if there were 64 responses the first day, how many were there on the fourth day?