CREATE TABLE table_20512 ("Line" TEXT, "Terminals" TEXT, "Status" TEXT, "Length" TEXT, "Total number of stations" FLOAT, "Operator" TEXT)

How many lengths of line 3 are given?
SELECT COUNT("Length") FROM table_20512 WHERE "Line" = 'Line 3'
SELECT COUNT("Length") FROM "table_20512" WHERE "Line" = 'Line 3'