The sum of three numbers is 300. If the ratio between first and second be 5:9 and that between second and third be 9:11, then second number is

Let us assume the ratio factor is x.
Then the three numbers be 5x , 9x and 11x respectively.
Then according to question,
5x + 9x + 11x = 300
⇒ 25x = 300
⇒ x = 12
So, the second number is 9x = 9 x 12 =108