4r^2=4 if r=1
2s^3=250 if s=5
F=ar^t if the half-life is 96 years...
.5=r^96
ln(.5)=96lnr
ln(.5)/96=lnr
r=e^((ln.5)/96)
f=800e^(336(ln.5)/96)
f=70.71
So about 71mg will remain after 336 years.
-1+z because 7-8 would be -1 and positive 3-3 would just be the variable after