Answer: 
Step-by-step explanation:
Given : Number of choices for novels = 4
Number of choices for plays = 6
Number of choices for poetry books = 5
Number of choices for nonfiction books = 5
Total books =4+6+5+5=20
If he wants to include all 4 novels, then the number of books left to select = 9-4=5
Remaining choices for books = 20-4=16
Number of combinations of n things taking r at a time : 
Then, the number of different reading schedules are possible :_

Hence, the required answer is
.
Answer:
6 and 7
Step-by-step explanation:
x + y = 13
xy = 42
I just listed the two equations out and the answer just popped out. The trick to this is just thinking about two numbers that obviously both below 13 that add up to it. 6 and 7 is the solution.
About 9-10 times(when you divide you get a decimal)