Since the GCF of K and 24 is 6. K cannot be a multiple of 12 or 24 since the GCF would be 12 or 24.
The multiples of 6 between 30 and 50 are 36, 42, and 48.
We cannot get 36 since it is div. by 12.
We cannot get 48 since it is div. by 24.
Therefore the number is 42.