Complex sentence: The Zambales Mountains are on the western side of Luzon, in the Philippines, which seperate the central plain from the China Sea and extend out as Bataan Peninsula, so as to help form Manila Bay.
Split into simpler sentences: The Zambales Mountains are on the western side of Luzon, in the Philippines. The mountains seperate Luzon's central plain from the China Sea and extend out as Bataan Peninsula, so as to help form Manila Bay.