The highlighted ones are the correct answers, but can anyone show me how to work them?

Cox Engineering performs cement core tests in its laboratory. The tom cement core tests in its laboratory. The following standards have been set for each core test performed: Direct materials .......... Direct labor ................. Variable manufacturing overhead...... Standard Hours or Quantity 3 pounds 0.4 hours 0.4 hours Standard Price or Rate $0.75 per pound S12 per hour S9 per hour During March, the laboratory performed 2,000 core tests. On March 1 no direct materials (sand) were on hand. Variable manufacturing overhead is assigned to core tests on the basis of standard direct labor-hours. The following events occurred during March: 8,600 pounds of sand were purchased at a cost of $7,310. 7,200 pounds of sand were used for core tests. 840 actual direct labor-hours were worked at a cost of $8,610. Actual variable manufacturing overhead incurred was $3,200. 4. The materials price variance for March is: A. $860 unfavorable B. $860 favorable C. $281 unfavorable D. $281 favorable PIC 0.75 0.7 5. The materials quantity variance for March is: A. $900 favorable B. $1,950 favorable C. $1,950 unfavorable D. $900 unfavorable ST 6. Heersink Corporation bases its predetermined overhead rate on variable manufacturing overhead cost of $10.50 per machine-hour and fixed manufacturing overhead cost of $108,108 per period. If the denominator level of activity is 2,700 machine-hours, the fixed element in the predetermined overhead rate would be: A $1,050.00 B. $40.04 C. $10.50 D. $50.54