Suppose That T Hours After Being Placed in a Freezer $f ( t ) = 70 - 12 t + \frac { 4 } { t + 1 }$

Short Answer

Suppose that t hours after being placed in a freezer, the temperature of a piece of meat is given by $f ( t ) = 70 - 12 t + \frac { 4 } { t + 1 }$ . How fast is the temperature of the meat falling 3 hours after being placed in the freezer?
Enter your answer as a reduced fraction of the form $\frac { a } { b }$ , no units.