Answer:
C = (5/9) F - (160/9)
They both read equal at Z = - 40
Explanation:
We are looking for a linear function so we can write the following condition
Y = aX + b
Applying it to the exercise we got C = a F + b
Let's use the facts that C = 0 when F = 32 and C = 100 when F = 212
0 = 32 a + b (1)
100 = 212 a + b (2)
From (1) b = - 32 a , when we replace this in (2) we obtain a = (5/9)
and b = - (5/9)32 = - 160/9
Finally the linear function is C = (5/9) F - (160/9)
Both readings are equal at a Z number so
Z = (5/9) Z - 160/9
(4/9) Z = -160/9 and Z = - 40