I need help with E and F. Please explain because I tried a couple solutions an it says it was wrong.

The standards for one case of liquid weed killer are Direct materials Direct labor Variable overhead (based on machine hours) 5 lbs @ $ 6.80/lb 2.4 hrs @ $14.00/hr 1.5 hrs @ $4.50/hr During the week ended May 6, the following activity took place 2,910 machine hours were worked 11,400 lb of raw material were purchased for inventory at a total cost of $80,940 1,900 cases of finished product were produced 9,260 lb of raw material were used 4,420 labor hours were worked at an average rate of $14.35 per hour $12,513 actual variable overhead costs were incurred Required: Calculate each of the following variances and provide plausible explanations for the results: (Do not round intermediate calculations. Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable.) a. Price variance for raw materials purchased. $ b. Raw materials usage variance c. Direct labor rate variance d. Direct labor efficiency variance e. Variable overhead spending variance f. Variable overhead efficiency variance 3,420 U $1,632 F $1,547 U $1,960 F