Electric zero produces relay units for generators. each relay has a standard material cost of $67. standards call for two relays per generator. in july, the company purchased 120 relays for $7,560. the company used 104 relays in the production of 50 generators, with 4 relays damaged in the installation process. the standard quantity of labor is 20 hours per generator, with a standard wage rate of $23. the company incurred 1,020 labor hours at a cost of $22,950. how much is the material quantity variance?