A certain number of machines can do a work in 75 days. If there were 6 machine more it could be finished in 15days less. How many machines are there?  Answers.
A) 20  B) 24  C) 25  D) 30  E) 32
Number of machines = 6* (75-15)/15= 
<gadget id="calculator">6* (75-15)/15</gadget>
<output>24</output>
24 machines   Answer is 24
<result>B</result>
A certain number of machines can do a work in 75 days. If there were 6 machine more it could be finished in 15days less. How many machines are there?