CREATE TABLE table_204_540 (id DECIMAL, "name" TEXT, "town" TEXT, "deanery" TEXT, "vicariate" TEXT, "founded" DECIMAL, "original ethnic community" TEXT)

what was the difference , in years between the founding of st. agnes and the founding of good shepherd ?
SELECT ABS((SELECT "founded" FROM table_204_540 WHERE "name" = 'st. agnes') - (SELECT "founded" FROM table_204_540 WHERE "name" = 'good shepherd'))
SELECT ABS((SELECT "founded" FROM "table_204_540" WHERE "name" = 'st. agnes') - (SELECT "founded" FROM "table_204_540" WHERE "name" = 'good shepherd'))