The formula for Gross National Product (GNP) relates it to Gross Domestic Product (GDP) by accounting for net factor income from abroad (NFIA). The relationship is GNP = GDP + NFIA. NFIA is calculated as the income earned by domestic residents from factors of production owned abroad (X) minus the income earned by foreign residents from factors of production owned domestically (M). Therefore, M is the factor income paid to foreign nationals within the domestic economy.