x = 3 and 8 gives an LCM of 24 but 3 and 8 haven't got a GCF of 2.
To give and LCM of 2 x must be even so we can try x = 2*3 = 6.
The LCM of 6 and 8 :- 6*8 = 48 But its not lowest multiple
Dividing by 2 we get 48/2 = 24 which is the LCM of 6 and 8 - and their GCF is 2.
So the value of x is 6