well since the lines run together and might be corroded badly, cut the bad line at the rear and disconnect the fitting, and remove it from the master cylinder. then run a new line next to the bad line, zip tie it carefully to the old line, and then connect it to the master cylinder and the rear drums. i had to do brake lines on my aunts 95 metro and i didnt bother taking out both rear brake lines because of that they ran next to the fuel pressure and return lines and they were rusted to shit.