Every day of the year throughout the world, about twenty million paper bags and the newspapers are screwed and thrown away. Making paper requires a lot of wood pulp and the work of millions of workers. Many countries have had plans to recycle waste paper to save money and labor. In countries where there is the cooperation of the public, paper mills recycle as much as sixty percent of waste paper. Their simple work is to take away the ink, crush it up and make it into pulp again. For every ton of recycled newsprint, twelve trees can be saved. We can insist that the more paper people save, the more trees are preserved. The word "it" in line 5 refers to..... Giải thích giúp mình nữa nhé ạ.