CREATE TABLE table_51694 ("Locomotive" TEXT, "Type" TEXT, "Builder" TEXT, "Builder's No." TEXT, "Built" FLOAT, "Entered service" FLOAT, "Withdrawn" FLOAT)

With a Type of 4-6-4t, what is the sum Withdrawn?
SELECT SUM("Withdrawn") FROM table_51694 WHERE "Type" = '4-6-4t'
SELECT SUM("Withdrawn") FROM "table_51694" WHERE "Type" = '4-6-4t'