Exponential decay-Carbon Dating

when an animal dies (t=0) the cabon-14 (which has a half life of 5730 years) begins to decay. The percent of carbon-14 present at time t, in years, is given by N=100(0.5)^t/5730

I know the basic shape is 0.5^t

and 100(0.5)^t is a vertical shift, but i cant figure out what transformation 0.5^t/5730 is,

im also not sure which points to begin with (0,1) and (1,5) OR (1,0) (5 1)?

AND THEN

determine the age of a bone if it now contains 75% of the carbon 14 it had when the animal died (t=0)

please AND THANKYOU