As shown in the figure, a network of resistors is connected to a battery of \( 24 \, \text{V} \) with an internal resistance of \( 3 \, \Omega \). The currents through the resistors \( R_4 \) & \( R_5 \) are \( I_4 \) & \( I_5 \) respectively. The values of \( I_4 \) & \( I_5 \) are :
