CREATE TABLE table_202_80 (id NUMBER, "name" CLOB, "metres" NUMBER, "feet" NUMBER)

how much higher , in feet , is marmolada than vernel ?
SELECT (SELECT "feet" FROM table_202_80 WHERE "name" = 'marmolada') - (SELECT "feet" FROM table_202_80 WHERE "name" = 'vernel')
SELECT (SELECT "feet" FROM "table_202_80" WHERE "name" = 'marmolada') - (SELECT "feet" FROM "table_202_80" WHERE "name" = 'vernel')