15.a) 8 b) y+2 c)y-1
16. 2n
17. 2n+1 or 2n-1
18. a) (3p+4q) b) 5-(3p+4q)
Explanation:
As per the given question here are the solutions:
15. a) 6 is an even number. so next even number is 6+2 = 8
b) y is an even number, so next even number is y+2
c) y is an even number, so largest odd number less than y will just before number of y that is y-1
16. Since all the even number is a multiple of 2 so, any even number can be written as 2n where n is any integer.
17. Any even number can be written as 2n where n is any integer.
So, any odd number can be written as 2n+1 or 2n-1
18. a) Given,
Each book costs = p
Number of books = 3
Total amount of books = 3p
Again,
Each pen costs = q
Number of pens = 4
Total amount of books = 4q
Total amount of books and pens = 3p+4q
b) The change from 5 cents will be 5-(3p+4q)