Math Help: I did the problem but I dont think Its correct?

Math Help: I did this problem but it doesnt look correct?
An employer pays $3,000 per month for rent office space, and pays a total of 12 employees (including yourself) $1,000 per month plus a bonus of $10 for each unit of work completed by the worker that month. Suppose also that your employer makes $18 (gross) per unit of work by an employee.
A.Find your monthly salary S(x) as a function of x, the number of units of work you complete that month.
B.If all of your co-workers produce/sell (on average) x units per month, find the monthly profit P(x) of your employer Phil Bates as a function of x.

A. An employee who makes x units per month will receive 1000 base pay plus 10x for the work completed, for a monthly wage of

S(x) = 1000 + 10x

B. If all the workers produce an total of x units per month, then each worker's wage will average S(x/12). With 12 employees, this means the employer pays a total of 12S(x/12) in wages, plus 3000 for rent. However, x units of work are also produced, each unit of which brings $18 for the employer, for a total of 18x dollars of revenue. Profit will be the revenue minus the costs to the employer, or

P(x) = 18x - (3000 + 12S(x/12))
= 18x - 3000 - 12S(x/12)
= 18x - 3000 - 12*(1000 + 10(x/12))
= 18x - 3000 - 12000 - 10x
= 8x - 15000

Note: The wording of the problem is ambiguous on what x should represent. The difference between John V's answer for part B and mine reflect the different ways in which we interpreted the problem. John V has defined x as the AVERAGE output of EACH worker during the month; I have defined x as the TOTAL output of ALL 12 workers during the month. I almost went John V's way myself but reread the problem and decided that x was supposed to be the total output rather than that for each worker. This difference aside, we came up with the same answer.

A. S(x) =1000 + 10x

B. P(x) = 18*12x - 3000 - 12(1000 + 10x) = 216x - 120x - 15000 = 96x - 15000.

x = no. of units by an employee

My earnings per month:
$10x + $1,000 Answer

Phil Bates profit per month:
12($18x) - 12($10x) - $3,000 - $12,000
$216x - $120x - $3,000 - $12,000
$96x - $15,000 Answer