Hi amrit,

     I think below code will help you.

trigger RFPupdate on RFP__c (before insert, before update) {

	Set<Decimal> comp = new Set<Decimal>();
	Set<Decimal> bid  = new Set<Decimal>();
	Set<Decimal> inc  = new Set<Decimal>();
	List<String> aud  = new List<String>();
	List<String> stage = new List<String>();
	List<String> stage2 = new List<String>();
	List<String> market=new List<String>();
	List<String> ratecard =new List<String>();
	List<Id> opp=new List<Id>();
	Map<String, RFP__c> rfpsMap = new Map<String,  RFP__c>();
	List<RFP__c> rfpListUpdate = new List<RFP__c>();
	
	for(RFP__c r : trigger.new){

		//put current RFP in to rfpsMap
		if(r.Completes_Required__c != null || r.Bid_LOI_in_minutes__c != null || r.Incidence_Rate__c != null || 
			((r.Audience__c == 'B2B' || r.Audience__c == 'Gen Pop') && r.Stage__c == 'RFP_Received') || 
			r.Market__c != null || r.Rate_Card__c != null || r.Opportunity__c!=null) {
			
			rfpsMap.put(r.Id, r);
		}
		
		if(r.Completes_Required__c != null){
			comp.add(r.Completes_Required__c);
		} 
		if(r.Bid_LOI_in_minutes__c != null){ 
			bid.add(r.Bid_LOI_in_minutes__c);
		}
		if(r.Incidence_Rate__c != null){
			inc.add(r.Incidence_Rate__c);
		}
		if((r.Audience__c == 'B2B' || r.Audience__c == 'Gen Pop') && r.Stage__c == 'RFP_Received'){    
			aud.add(r.Audience__c);
		}
		if(r.Market__c != null){
			market.add(r.Market__c);
		}
		if(r.Rate_Card__c != null){
			ratecard.add(r.Rate_Card__c);
		}
		if(r.Opportunity__c!=null){
			opp.add(r.Opportunity__c);
			system.debug('Opp*****'+opp);
		}
	}
	 
	//If audience is B2B or Genpop
	try{
		
		if(aud.size()> 0){
			Map<Decimal, CPI__c> cpi1 = new Map<Decimal, CPI__c>();
		 
			for(CPI__c obj1 : [SELECT Id, Bid_LOI_in_minutes__c,Actual_CPI__c,Incidence_Rate__c,Actual_CPIchanged__c,Audience__c,Stage__c, Completes_Required__c,Name,Market__c  FROM CPI__c 
								WHERE (Bid_LOI_in_minutes__c IN :bid AND  Completes_Required__c IN: comp AND Incidence_Rate__c IN:inc AND Audience__c IN:aud AND Name IN:ratecard AND Market__c IN:market  )])
			{
				cpi1.put(obj1.Completes_Required__c , obj1);
				system.debug('CPI'+cpi1);
			}
			
			// We have all the reference data we need, last loop on the each Opportunity
			
			if(!rfpsMap.isEmpty()){
				for(RFP__c rf1: rfpsMap.values()){
					if(cpi1.containsKey(rf1.Completes_Required__c)) {
						system.debug('_____RFP_______'+rf1);
						rf1.Actual_CPI__c = cpi1.get(rf1.Completes_Required__c).Actual_CPIchanged__c;
						system.debug('_______ActualCPI______'+rf1.Actual_CPI__c);
						if(rf1.Proposed_CPI__c == 0.00 ){
						rf1.Proposed_CPI__c= cpi1.get(rf1.Completes_Required__c).Actual_CPIchanged__c;
						system.debug('_______ProposedCPI______'+rf1.Proposed_CPI__c);
					}else {
						rf1.Actual_CPI__c =0.00;
					}

					// adding to rfpListUpdate
					rfpListUpdate.add(rf1);
				}
			}
			
		}
		if(!rfpListUpdate.isEmpty()){
			upsert rfpListUpdate;
		}
	} catch(exception e){ }
	
}