Statement I :
$ 25^{13} + 3^{13} \quad\text{and}\quad 20^{13} + 8^{13} $
divisible by $ (25 + 3) $ and divisible by $ (20 + 8) $
$ \therefore $ divisible by $ 7 $
Statement II :
Let $ R = (7 + 4\sqrt{3})^{25} = I + f $
$ R' = (7 - 4\sqrt{3})^{25} = f' $
$ \therefore R + R' = I + f + f' = 2^{25} C_0 7^{25} + 25C_2 7^{23}(4\sqrt{3})^2 + \ldots $
$ I + f + f' = \text{even integer} $
$ \Rightarrow I = \text{odd integer} $
$ \therefore 0 < f + f' < 2 \Rightarrow f + f' = 1 $
$ \therefore $ Both the statements are correct