Mr. K’s is a very popular hair salon. It offers high-quality hair-styling and physical relaxation services at a reasonable price, so it always has unlimited demand. The service process includes five activities that are conducted in the sequence described below. (The time required for each activity is shown in parenthesis):

Activity 1: Welcome a guest and offer homemade herb tea. (10 minutes)

Activity 2: Wash and condition hair. (10 minutes)

Activity 3: Neck, shoulder, and back stress release massage. (10 minutes)

Activity 4: Design the hair style and do the hair. (30 minutes)

Activity 5: Check out the guest. (5 minutes)

Three servers (S1, S2, and S3) offer the services in a worker-paced line. The assignment of tasks to servers is the following:

S1 does Activity 1.

S2 does Activities 2 and Activity 3.

S3 does Activities 4 and Activity 5.

Assume a wage rate of $10 per hour. What are the direct labor costs (in $) for one guest? (The accuracy should be of two digits after the decimal places.)

Please include the explanation.