A transformer has an efficiency of $80\%$ and works at 100 volt and 4 kw. If the secondary voltage is $240\;volt$ calculate the primary and secondary currents

Question

$\begin{array}{1 1} I_p= 40\;A,I_s=13.3\;A \\ I_p= 13.3\;A,I_s=40\;A \\ I_p= 4\;A,I_s=13.3\;A \\ I_p= 4\;A,I_s=1.33\;A \end{array}$