A TaTa company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 14 hrs and a machine of type S does the same job in 7 hours. If the company used the same number of each type of machine to do the job in 2 hours, how many machines of type R were used?	Select the correct option.
A) 3 B) 4 C) 6 D) 9 E) 12
Rate of machine R =1/14   Rate of machine S =1/7   since same no of machines used for R and S to do the same work in 2 hrs   So collective rate needed to finish the work in 2 hrs= 1/2   Let the no of machine be x   So, x/14 +x/7 =1/2   3x/14=1/2   x=14/6=2.3=3   So no of machine R is 3   3nswer 3
<result>A</result>
A TaTa company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 14 hrs and a machine of type S does the same job in 7 hours. If the company used the same number of each type of machine to do the job in 2 hours, how many machines of type R were used?