Question 118234
(Number of scientists)(hours worked per scientist) = Total hours
(rate1) = (rate2)
rate1 = rate2 =  (1 big machine / total hours)
{{{1/(6*15*20) = 1/(5*12*d)}}}
{{{1/1800 = 1/60d}}}
{{{60d = 1800}}}
{{{d = 30}}}days answer