Question

A pendulum takes 6.0 seconds to swing through 5 complete cycles. What is the period of the pendulum?

Answer 1

When you look at this, you might not be sure which way to divide ...
Should you divide  6 by 5  or  5 by 6 ?

Here's a case where you can use your units to decide.

The question wants to know the 'period'.  That's a length of time,
so the answer needs to have units of time.

If you divide 'cycles' be 'time', you'll get  'cycles/second'.
That's Hz.  It's frequency, not time.

If you divide 'time' by 'cycles', you'll get 'seconds/cycle'.
That's time, and it's exactly the definition of 'period'.

            Period  =  (6 seconds) / (5 cycles)

                         =    (6 / 5)  seconds/cycle

                         =     1.2  seconds