A roast is taken from the refrigerator (where it had been for several days) and placed immediately..

A roast is taken from the refrigerator (where it had been
for several days) and placed immediately in a preheated oven to cook. The
temperature R = R(t) of the roast t minutes after being placed in the oven is
given by

a. What is the temperature of the refrigerator?

b. Express the temperature of the roast 30 minutes after
being put in the oven in functional notation, and then calculate its value.

c. By how much did the temperature of the roast increase
during the first 10 minutes of cooking?

d. By how much did the temperature of the roast increase
from the first hour to 10 minutes after the first hour of cooking?