ter 6 If variable selling and administrative expenses totaled $120,000 for the year (80,000 units at $1.50 each) and the planned variable selling and administrative expenses totaled $136,500 (78,000 units at $1.75 each), the effect of the unit cost factor on the change in Oa. $19,500 increase Ob. $19,500 decrease Oc. $20,000 increase od, $20,000 decrease margin is