Carrying out some maths on an ADC variable from an microcontroller

Still fairly new to App Inventor 2, but have made some basic apps, and now trying to do some basic maths.

I have a MSP430 microcontroller connecting via  HC06 Bluetooth device, I can receive the ADC value but I want to convert this into a temperature.

I save the ADC value to a global variable called ADC, and can display this but running out of idea's how to convert it.  I have tried various procedures and maths but I cannot seem to perform any calculation when a variable is used, if I use basic numbers it's fine.  A screen cap of some of my code is below, but only the upper part "clock" is working at the moment.

Any help or guidance would be appreciated?

try the ReceiveText method, see also here

A simple Bluetooth Chat with App Inventor 2