hey, ive been given the below problem in an assignment and have no idea how to solve it. Please help.

Prblem: A solution of iodide ions gave a fluorescence reading of 62%T. A 10 ml aliquot of a 0.2 mg/L iodide standard was added to 5ml of the solution. What is the concentration of iodide in the solution if the fluorescence intensity of the spiked solution was 84%T?

i know i must use the formula

F= 2.303.K.0.P.E.b.c

where F= fluorescence

K= Fraction of emitted radiation being

collected, usually 90 degrees

O= fraction of species in sample which

deactivates to yield the measured emission.

b= light path

c= concentration

E= molar extinction coefficient

p=incident radiation

any help would be great.

thanks