The equation y= -5/2x + 15 represents the number of remaining chapters, y, in Megan's book after she reads x hours. What does the slope represent?
1) The slope represents the rate at which Megan reads the chapters.
2) The slope represents the number of chapters Megan has already read.
3) The slope represents the total number of chapters in Megan's book.
4) The slope represents the number of hours Megan has spent reading.