Answer:
Let's try to find a linear relation like:
T(h) = a*h + b
where a is the slope and b is the y-intercept.
h is the number of hours after midnight.
T is the temperature at the time defined by h.
We know that at midnight, the temperature is 12.8°F.
At midnight, we have h = 0, then:
T(0) = a*0 + b = 12.8°F
b = 12.8°F
Now we know that our function is:
T(h) = a*h + 12.8°F
We also know that the temperature fell 1.4 °F each hour for six hours.
Then the slope will be -1.4°F
We can write the linear relationship as:
T(h) = -1.4°F*h + 12.8°F (for 0 ≤ h ≤ 6)
Where we have a restriction in the possible values of h, because we know that this model only works for six hours after midnight,