In Company A, the total monthly payroll for the 12 factory workers is $18,000 and the total monthly payroll for the 40 office workers is $100,000. By how much does the average (arithmetic mean) monthly salary of an office worker exceed that of a factory worker in this company?  Choose the correct choice from the following answers.
A) $600 B) $700 C) $800 D) $900 E) $1000
The average monthly salary of a factory worker is: $18,000 / 12 = $1500.   The average monthly salary of an office worker is: $100,000 / 40 = $2500.   The difference in average salary is: $2500 - $1500 = $1000.   The answer is $1000.  2500 -  1500= 
<gadget id="calculator">  2500 -  1500</gadget>
<output>1_000</output>
$1000.   The answer is $1000.
<result>E</result>
In Company A, the total monthly payroll for the 12 factory workers is $18,000 and the total monthly payroll for the 40 office workers is $100,000. By how much does the average (arithmetic mean) monthly salary of an office worker exceed that of a factory worker in this company?