I need help solving with a step by step on how to solve this problem

23) A partial standard cost card for the single product produced by Mercer Company is given below Direct materials: 3 pounds$8 per pound Direct labor: ? hours ? per hour Last period the company produced 4,000 units of product. Cost and other data associated with this production are given below Direct materials purchased and used, at $103,320 cost Direct labor cost incurred (10,400 hours) Materials price variance Labor efficiency variance $120,640 $2,520 Unfavorable $4,800 Unfavorable $640 Unfavorable Total labor variance etermine the number of pounds of direct materials purchased and used during the period