Areporter collected date on y, the current market value, in dollars, of a certain car for various years, x, after it had been purchased new. the equation below was fit to the date. y= 16,500-1500x. what does the slope of the graph of this equation represent

The slope is -1500 which is the number just to the left of 'x'. This value represents the rate of change of the value over time. Specifically, each year that goes by (aka every time x increases by 1), the value of y will drop by 1500. Recall that

slope = rise/run

so if slope = -1500, then rise/run = -1500/1 which makes the "rise" to be -1500, which is really a decrease of 1500.

In short, the car is losing $1500 of value each year. Keep in mind that this is an approximate look at the data and not 100% exact. 

Where are the functions?