Urgent - Controlling multiplexer outputs - Sensor Network

Yes definitely,

I do know all of these equations, the thing is I don't know if I can control these.
One of these channels represent the analogue value of a temperature sensor, but I want to convert it into Celsius and I know it's equation, yet where in the code and how can I control each channel separately?
Channel 0 - temperature values
Channel 1 - humidity values
Channel 2 - gas values
Channel 4 - pressure values

I hope you understand.