Without knowing your tables and the interaction between them, I can't be specific and accurate. But what you want to do is a JOIN.
Try
SELECT a.quantity1, b.quantity2 , (a.quantuty1 * b.quantity2) AS ukupno
FROM dbo.table2 a
JOIN (SELECT kolicina AS quantity2 FROM dbo.radni_nalog_roba
WHERE id_fakture = (SELECT MAX(id) FROM dbo.radni_nalog_lista)) b
ON a.ID = b.id_fakture
or similar.