i guess u meant the 24 hour clock .... if it is 12 hour clock ..... the answer is already thr in the question = half past 6
if it is the 24 hour clock ... the answer will be 18 : 30
reason : now if u c a 12 hour clock ... after 12 noon .... it becomes 1 again the 2 then 3 ... so on ....
but in the case of a 24 hour clock ... after 12 noon it goes on like ... 13 , 14, 15, ect ...
so 12 : 30 + 6 = 18:30