A certain radioactive element decays over time according to the equation \(y=R\ (1\ /\ ^{x/200}\)[ly equals R times one half to the power of the quantity x over 300], where \(R\) equals the number of grams that were present initially and \(x\) equals time in years. If 1000 grams were present initially, how many grams will remain after 900 years?

W) 62.5

X) 125

Y) 250

Z) 500
X) 125