The average of 5 consecutive old positive integers is 9. The least one amongt them is

Let the 5 consecutive positive integers be x + 1, x + 3, x + 5, x + 7, x + 9
Average = (Sum of all terms) / (Number of terms)
⇒ 9 = [(x + 1) + (x + 3) + (x + 5) + (x + 7) + (x + 9)]/5
⇒ 9 = (5x +25)/5
⇒ 45 = 5x + 25
⇒ 5x = 45 - 25
∴ 5x = 20 ⇒ x = 4
The least one is x + 1 = 4 + 1 = 5