Here's one that selects from two fields and adds another calculated one
SELECT Deductions.Heading, Sum(IIf(FinancialYear([TrDate])=FinancialYear(Date()),(([Debits]/FinancialWeek([TrDate])*(52-FinancialWeek([TrDate]))+([Debits]))),[Debits])) AS SumOfDebits, FinancialYear([TrDate]) AS FYear
FROM Deductions
WHERE (((Deductions.Heading)<>"Receipts") AND ((FinancialYear([TrDate]))>FinancialYear(Date())-3))
GROUP BY Deductions.Heading, FinancialYear([TrDate]);
UNION SELECT Deductions.Heading, Sum(IIf(FinancialYear([TrDate])=FinancialYear(Date()),(([Credits]/FinancialWeek([TrDate])*(52-FinancialWeek([TrDate]))+([Credits]))),[Credits])) AS SumOfCredits, FinancialYear([TrDate]) AS FYear
FROM Deductions
WHERE (((Deductions.Credits)>0) AND ((FinancialYear([TrDate]))>FinancialYear(Date())-3))
GROUP BY Deductions.Heading, FinancialYear([TrDate]);
UNION SELECT "Profit" AS Profit, Sum(IIf(FinancialYear([TrDate])=FinancialYear(Date()),(([Credits])-(IIf(
="EquipPurchase",0,[Debits])))/FinancialWeek([TrDate])*(52-FinancialWeek([TrDate]))+([Credits])-(IIf(
="EquipPurchase",0,[Debits])),([Credits])-(IIf(
="EquipPurchase",0,[Debits])))) AS Expr1, FinancialYear([TrDate]) AS FYear
FROM Deductions
WHERE (((FinancialYear([TrDate]))>FinancialYear(Date())-3))
GROUP BY "Profit", FinancialYear([TrDate]);