Equation for Relative Humidity at a given Temperatur from Relative Humidity

Nope also not a option, in a nutshell i wanna check if its worth to take outdoor air (intake sensor) into the room, thats why i wanna have a humidity readin which is temperature compensated with the indoor air, that why i should get an estimate what humidity ends up in the room and can look if its worth taking THAT air in

the same i do for temperature, but temperature doesnt need to be compensated with anything, thats why this part should be easy..

a 3rd sensor would be redundant because i already have an outtake sensor