Inverting value

i have my inputs configured to send them true mqtt.
but i need to invert my value -2700 needs to be 2700 and vice versa.
how can i configure this ?

Are the inputs correct to begin with? If not, either reverse the direction your current transformer points on its wire, or multiply by -1 inside the sketch or in the inputs page of emonCMS or put a minus sign (’-’) in front of the number in “scales = …” in emoncms.conf
Do only one of these things.

If the inputs are correct in emoncms, then multiply by -1 just before you send the number to mqtt.