Sum two Numbers (state of items)

Setup, Configuration and Use Migration
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1

Hello,
I’m trying to translate my old rules in the new OH3 rule engine, but is very difficult and I don’t know how can I do.

My old rule was

rule "Consumo Istantaneo"
when
    Item Enel_Real_Power received update or
    Item FV_Real_Power received update
then 
	if (Enel_Real_Power.state > 0 && FV_Real_Power.state > 0) 
	{
		Ist_Consumo.postUpdate(FV_Real_Power.state as Number + Enel_Real_Power.state as Number)
		Ist_Prelievo.postUpdate(Enel_Real_Power.state)
		Ist_Immissione.postUpdate(0)
		Ist_Autoconsumo.postUpdate(FV_Real_Power.state)
		Ist_Produzione.postUpdate(FV_Real_Power.state)
	    } 
end

I try to do with blocky rules but these new code not work…

if ('MQTTEnergymonitor_EnelPotenzaReale' > 0 && 'MQTTEnergymonitor_PannelliPotenzaReale' > 0) {
  events.postUpdate('Ist_Consumo', ('MQTTEnergymonitor_EnelPotenzaReale' + 'MQTTEnergymonitor_PannelliPotenzaReale'));
}

Can you help me to see the light at the end ?

thank you