Answer:
y = -6 + 1.2*x is the answer I would use, but see the note below.
Explanation:
Let x = the number of minutes.
Let y = the temperature at any given time.
y = -6 + 1.2*x
This is the equation that you would use if you were calculating y with a calculator. If you are in a chemistry class it should be written as
y = - 6°C + 1.2°x/ min