Ahawk soars at an altitude of 1800 ft. if the hawk decends to the ground in 45 min. what is it's vertical speed.

1800/45 = 40

 so the vertical speed is 40 feet per minute

The plan is 100 songs downloaded equally on each week for 5 weeks, so,

100 songs/ 5 weeks; 20 songs per week.

Number of Weeks (x)              Songs left to download (y)
            1                                                  100
            2                                                  80
            3                                                  60
            4                                                  40
            5                                                  20 

The rate of change is 20 songs per week. 

y = mx + b, input in the STAT feature of the calculator.

m = -20
b = 120