Think of cancelling fractions:
[tex]\frac{12}{8} = \frac{3*4}{2*4} = \frac{3}{2} [/tex]
Because the '4' was on top and bottom,they cancelled themselves out.
You do the same thing with units.
Starting with 'inches', ending with yards. You want the inches to cancel.
Since the original units start on top. The inches in the ratio needs to be on the bottom so they cancel.
[tex]540 in * \frac{1 yd}{36 in} = \frac{540}{36} yds[/tex]
Answer: The unit 'yards' needs to be in the numerator.
