??????????????? "per annum" ??????????????... ??????????? yu tri tu pretend yuno Latin ?????????.... apparently yu want kompound interest on 15,625$ at 16%, 9 months... & kompound bi quarter... 1 quarter %=16/4=4%, so fakter=(1.04)^3=1.124864... $ yu oe=15,625*1.124864=17,576$... so interest=17,576 -15625=1,951$