CREATE TABLE table_202_80 (id DECIMAL, "name" TEXT, "metres" DECIMAL, "feet" DECIMAL)

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')