If seven machines working at the same rate can do 3/4 of a job in 30 minutes, how many minutes would it take two machines working at the same rate to do 3/5 of the job? Select the correct option:  A) 45  B) 60  C) 75  D) 84  E) 100
using the std formula   m1d1h1/w1=m2d2h2/w2   substituting the values we have   7*1/2*4/3=2*5/3*x (converted 30 min into hours =1/2)   14/3=10/3*x   x=7/5 hour   so 84 minutes   ANSWER:84
<result>D</result>
If seven machines working at the same rate can do 3/4 of a job in 30 minutes, how many minutes would it take two machines working at the same rate to do 3/5 of the job?