A certain clock marks every hour by striking a number of times equal

I guess your generation has had no exposure to the clocks of the old days.
In the old days, the clocks used to strike at the hour i.e. at 2 o clock, you would hear 2 strikes. There would be a small interval between two strikes. The point was that watches/clocks were not common and often there was a single clock for a whole village. There would be loud strikes at every hour to inform everyone of the time. People could count the strikes to know what time it is.

Check out this youtube video of big ben to understand what a clock strike is: https://www.youtube.com/watch?v=rkXy20fUoic

at 6'o clock, there would be 6 strikes. First strike, then a short interval, the second strike, then a short interval and so on till the 6th strike. So there would be in all 5 intervals between 6 strikes. Similarly, between 12 strikes, there would be 11 intervals.

According to the question, the time spent in the strike and the interval is same.
At 6'o clock, the 6 strikes and the 5 intervals together take 22 sec so each strike and each interval takes 2 secs.

At 12'o clock, the 12 strikes and 11 intervals will take 2*(12+11) = 46 secs