The half-life of rhodium is about 30 seconds. you start with 500 grams. write an equation

Half life is the period of time after which half amount of element is decayed.

Half life of rhodium = 30 sec

Amount of rhodium = 500 grams

how to write the equation, if we know the half life and starting or initial amount of rhodium is:

N = 500 g (1/2)^(t / 30 sec) 

t is the time and

N is the amount of rhodium left at time t.