As shown in the figure, a network of resistors is connected to a battery of 24 V with an internal resistance of $3 \Omega$. The currents through the resistors $\mathrm{R}_4$ and $\mathrm{R}_5$ are $\mathrm{I}_4$ and $\mathrm{I}_5$ respectively. The values of $\mathrm{I}_4$ and $\mathrm{I}_5$ are :