High frequency clock from clocked RS latch
You can not use a JK or any other Flip-Flop unless you already have a clock.

Thus you can make a new clock signal with a lower frequency but not higher.
The nearest is a divide-by-two. Thus new_freq = old_freq/2.
With more FF's you can make a divide by 4,8,16 etc.

With some extra gates you can make a divide by 3, 5, 7.
You can not make a divide by a fraction unless you start using more special circuits like a PLL.