Maybe you could try
SELECT
a.CustomerName
,a.AgreementValue
,a.TotalValue - a.AgreementValue AS BlackAmount
,(SELECT SUM(PaidAmount) FROM AmountMaster WHERE AmountTypeId = 2 AND PaymentToId = 1 AND CustomerId = 8 AND PlaceId = 1) AS Paid2Me
,(SELECT SUM(PaidAmount) FROM AmountMaster WHERE AmountTypeId = 2 AND PaymentToId = 2 and CustomerId = 8 and PlaceId = 1) AS Paid2Builder
,Paid2Me - Paid2Builder AS DueAmount
FROM
CustomerDetails a
JOIN AmountMaster b ON a.CustomerId = b.CustomerId
WHERE
a.CustomerId = 8 AND b.PlaceId = 1