can some check my answer (24) is that correct?

Question

Answer 1

Yes, it is correct

Sin = O/H

Sin 30 = .5

12/H= .5

H= 12/.5 =24

Answer 2

Do not see your answer, but the angles tell you that this is a typical 3-4-5 triangle.   So if b is 3/5 of c, and  b is 12, then 12 is 3/5 of c .

The answer would be that c is 20.

Now I see that you mean that your answer is 24.  Sorry, that is incorrect.