Find the total payment of the orders by customers from San Francisco.
from San Francisco refers to City = 'San Francisco'; total payment refers to sum(MULTIPLY(UnitPrice, Quantity, SUBTRACT(1, Discount)))
SELECT SUM(T3.UnitPrice * T3.Quantity * (1 - T3.Discount)) AS TOTALPAYMENT FROM Customers AS T1 INNER JOIN Orders AS T2 ON T1.CustomerID = T2.CustomerID INNER JOIN `Order Details` AS T3 ON T2.OrderID = T3.OrderID WHERE T1.City = 'San Francisco'