Delta Corporation planned to sell one of its products for $148 per unit but actually sold each for $140, and planned to make and sell 1018 units but actually made and sold 1007 units. The sales-volume variance for revenue is $________. (If the variance is unfavorable, present your answer as a negative (e.g., -100), if it is a favourable variance, present as it is (e.g., 100)).