Question

Yannick and Jean are playing a guessing game with integers. Yannick wrote these clues to help Jean guess the unknown integer.

n + 6 greater-than-or-equal-to 15 and n + 5 less-than 15

What is the value of the unknown integer, n?
8
9
19
22

Answer 1

n + 6 ≥ 15 ⇒ n ≥ 9.
n + 5 < 15 ⇒ n < 10.
The only integer satisfying 9 ≤ n < 10 is 9.