Given that frequency is 5Ghz. We need to convert this to Cycles Per Second (cps). If 1 Hz is equal to 1 cps, then 5Ghz = 5,000,000,000Hz = 5000000000cps.

To get the duration of a clock cycle, you have to calculate the period which is simply 1/frequency or 1/cps.

This gives;

1/(5*10^9) seconds.

Regards :)