Hadi, I'm guessing they want you to write an equation that fits this.
If n is no less than 20, that means it can be 20 or greater. Same with being no more than 31.
n ≥ 20 and n≤ 31
This part can be confusing, where we combine them, with n in the middle. Because we start with the lowest number, the first sign switches because we are turning it around.
20 ≤ n ≤ 31
n is still greater than or equal to 20 and less than or equal to 31.
Hadi A.
11/07/16