In 6 hours heather reads 30 chapters of a book what is her rate in chapters per hour​

Ineed with number 6 , explain how to get 1978

Ateacher wanted to buy a chair, a bookshelf, two tables and a desk. she spent $900 for all five items and the chair and the desk combined 70% of her total. if the bookshelf cost $50, how much did each of the tables cost?

Typically a point in a three dimensional cartesian coordinate system is represented by which of the following answers in the picture !