How to add two sql column decimal values in normal select query

Question

I need to add row values from multiple column values from two tables. I have tried below and facing error. how to achieve this.

Note: I need to use as normal select query in my test script, and not as Stored Procedure or any other formats.

if (
    select count(Rate_Index_Value) 
    from LOAN_PAYMENTS 
    where Loan_ID = 17781 
    and Processing_End_Date > '9999') 
= 1
    select 
    'From LOAN_PAYMENTS table' as tbName, 
    Rate_Index_Value as Original_Interest_Rate, 
    * 
    from LOAN_PAYMENTS 
    where Loan_ID = 17781 
    and Processing_End_Date > '9999'
else
    begin
      select 
      'From LOAN table' as tbName, 
      Rate_Index_Value as Original_Interest_Rate, 
      * 
      from LOAN 
      where Loan_ID = 17781 
      and Processing_End_Date > '9999' 
      and Business_End_Date > '9999'
      
      select 
      'From LOAN_PARTY table' as tbName, 
      (BrokerDealer_Split + LendingBank_Split) as Original_Interest_Rate, 
      * 
      from LOAN_PARTY 
      where Loan_ID = 17781 
      and Processing_End_Date > '9999' 
      and Business_End_Date > '9999'
      (
        (select 
         Rate_Index_Value 
         from LOAN 
         where Loan_ID = 17781 
         and Processing_End_Date > '9999' 
         and Business_End_Date > '9999'
        ) 
        + 
        (
          select (BrokerDealer_Split + LendingBank_Split) 
          from LOAN_PARTY 
          where Loan_ID = 17781 
          and Processing_End_Date > '9999' 
          and Business_End_Date > '9999'
        )
     ) as Original_Interest_Rate
    end
go

i am getting error in the combined statement line under else condition.

>[Error] Script lines: 1-8 --------------------------
 Incorrect syntax near '+'.
 Msg: 102, Level: 15, State: 181

>[Error] Script lines: 1-8 --------------------------
 Incorrect syntax near ')'.
 Msg: 102, Level: 15, State: 181

Updated with my missing keyword: Actually i missed the 'select' keyword before the open bracket on the combined statement and so i was getting the error. After adding , it worked.

select (
        (select 
         Rate_Index_Value 
         from LOAN 
         where Loan_ID = 17781 
         and Processing_End_Date > '9999' 
         and Business_End_Date > '9999'
        ) 
        + 
        (
          select (BrokerDealer_Split + LendingBank_Split) 
          from LOAN_PARTY 
          where Loan_ID = 17781 
          and Processing_End_Date > '9999' 
          and Business_End_Date > '9999'
        )
     ) as Original_Interest_Rate