The temperature, , in degrees Celsius, of a cup of coffee placed on the kitchen counter is given by , where is in minutes since the coffee was put on the counter.

(a) Is positive or negative?
(Be sure that you are able to give a reason for your answer.)

(b) What are the units of ? help (units)

Suppose that and . Fill in the blanks (including units where needed) and select the appropriate terms to complete the following statement about the temperature of the coffee in this case.
At minutes after the coffee was put on the counter, its is and will by about in the next 30 seconds.