Answer:
346 is initial amount of radioactive isotopes.
Explanation:
The amount of a radioactive isotope decays in half every year.
The amount of the isotope can be modeled by

f(1)=173
We are given half life of isotope is 1 year.
f(x) represents the amount of isotope left after x years.
f(1) represents half amount of radioactive isotope.
If we x=0 into model


x=0 means initial value of time.
Therefore, 346 represents the initial amount of the radioactive isotopes.
Hence, 346 is initial amount of isotopes.