Zero is not an element of the set of natural numbers.
a. true
b. false

0 is a natural number. Every natural number has a successor. 0 is not the successor of any natural number. If the successor of equals the successor of , then equals .

Step-by-step explanation:

2.   2 3/5.

3.   2 1/2.

step-by-step explanation:

6 - 3 2/5

= 6 -   17/5

= 30/5 - 17/5

= 13/5

= 2 3/5 (answer).

5 1/4 - 2 3/4

= 21/4 - 11/4

= 10/4

= 2 1/2 (answer).