= 20,000 books Remaining number of books = 1,00,000 – 20,000 = 80,000 books which will be printed by machines Q and R Machines (Q + R)'s 1 hour's work = (
1
10
+
1
12
)×100000 =
11
60
×100000 =
55000
3
books Hence, time taken by both the machines to print the remaining books =