21. Anson Corporation planned to sell one of its products for $154 per unit but actually sold each for $138, and planned to make and sell 1095 units but actually made and sold 1000 units.

The sales-volume variance for revenue is $________. (If the variance is unfavourable, present your answer as a negative (e.g., -100), if it is a favourable variance, present as it is (e.g., 100)).