Verified answer

✎ [tex] \: \huge\sf{ANSWER} \: [/tex]

[tex]\boxed {27}[/tex]

Numbers divisible by 9:

{ 9, 18, 27, 36, 45 ...}

But are not divisible by 6:

{9, 27, 45}

But Greater than 10 and less than 40:

27

Therefore the answer is 27