labor hours per month and is $$9$ per direct labor hour, whereas the predetermined variable overhead rate is $$3$ per direct labor hour.

Note: In answering the following questions, do not use negative signs with your answers.

a$.$ Compute overhead variances using a four$-$variance approach.

b$.$ Compute overhead variances using a three$-$variance approach.

c$.$ Compute overhead variances using a two$-$variance approach.