Since the pizza was heated at a constant rate, the table describes a linear relationship.
Moreover, the rate of change of this relationship corresponds to the rate at which the pizza was heated.
The table of values shows that for each increase 6, minutes in time, temp increased by 45 degrees Celsius. The rate at which the pizza was heated is the ratio of those corresponding differences
In conclusion, the pizza was heated at a rate of 7.5 degrees Celsius per minute.