Three printing press P Q and R can print 1 lack books in 5 hrs 15 hrs and 10 hrs respectively If all...........

Explanation:

Answer & Solution
Answer – 1 pm
Solution:
Time taken by P = 5hrs, Q = 15hr and R = 10 hrs
(1/5+1/15+1/10)*2 + (1/5 + 1/15)*X = 1 (X = time taken to do remaining work)
after solving we get X = 1. So 2+1 = 3hrs. i.e at 1pm work will be completed.