(2,60)(4,240)......t = x and d(t) = y
average rate of change (slope) is (y2 - y1) / (x2 - x1)
slope = (240 - 60) / (4 - 2) = 180/2 = 90 m/s
It represents the average distance traveled by the object between 2 seconds and 4 seconds
Differentiate both sides wrt 
:
By the chain rule, we get
Solve for 
:
Let the temperature at 10am be x, then
x + 8 = 56
x = 56 - 8 = 48 degrees F
Let y be the temperature at 8am, then
y - 2 = 48
y = 48 + 2 = 50 degrees.
