The formula for converting from degrees Fahrenheit F to degrees Celsius C is C=5/9 (F-32). Convert each temperature.

a. City X temperature: - 31∘F

b. City Y temperature: - 45∘C

c. City Z temperature: - 40∘C

I don't know if the asker meant those to all be in Fahrenheit; let's assume it's correct as written.

The interesting thing that this will teach us is that around - 40 degrees the Celsius and Fahrenheit scales are about the same.

F=-31

C = (5/9) (F - 32) = (5/9) (-31 - 32) = (5/9) (-63) = 5 (-7) = - 35

Answer for a: - 31°F = - 35°C

The next two give us C and we want F. Let's solve the general formula for F.

C = (5/9) (F - 32)

(9/5) C = F - 32

F = (9/5) C + 32

C = - 45

F = (9/5) (-45) + 32 = - 81 + 32 = - 49

Answer for b: - 45°C = - 49°F

C = - 40

F = (9/5) C + 32 = (9/5) (-40) + 32 = - 72 + 32 = - 40

They're the same!

Answer for c: - 40°C = - 40°F