Answer:
1. rooster method- listing the elements in any order and enclosing them with brace
Example:A={ january, february ,march...december}B={1,3,5...}
2.rule mathod- giving a descriptive phrase that will clearly identify the elements of the set. example:C={ days of the week}D={odd numbers}
3. set builder notation i.e B = {x | 1 < x < 10 and 3 | x}
I HOPE IT HEPS :>
AND HAVE A NOICE DAY(。’▽’。)