Northern Companys budgeted and actual sales for 2009 were as follows. Product Budgeted Sales Actual Sales A 6,000 units at $8.00 per unit 6,810 units at $7.80 per unit B 5,000 units at $10.00 per unit 4,720 units at $10.40 per unit Part (a): Calculate the sales volume variance. Part (b): Calculate the sales price variance. Part (c): Calculate the total sales variance.