In a radioactive sample, $$_{19}^{40}K$$ nuclei either decay into stable $$_{20}^{40}Ca$$ nuclei with decay constant $$4.5 \times 10^{-19}$$ per year or into stable $$_{18}^{40}Ar$$ nuclei with decay constant $$0.5 \times 10^{-10}$$ per year. Given that in this sample all the stable $$_{20}^{40}Ca$$ and $$_{18}^{40}Ar$$ nuclei are produced by the $$_{19}^{40}K$$ nuclei only. In time $$t \times 10^9$$ years, if the ratio of the sum of stable $$_{20}^{40}Ca$$ and $$_{18}^{40}Ar$$ nuclei to the radioactive $$_{19}^{40}K$$ nuclei is 99, the value of t will be,
[Given: $$\ln 10 = 2.3$$]