Write the  over } and the  over 
so the whole "building" will be 4 "stories"
high.



Put parentheses around the numerator and the
denominator:



Look at all four denominators, ,,,and 
Their LCD is . So multiply by 
which just equals . But make it four "stories" 
high also by putting each of the 's over
 like this



Now since this just equals to , we can multiply
it by our example without changing its value.

 

Now remove the parentheses by distributing:



The first term on top just becomes  which is
just 



The 's cancel in the second term on top, leaving
just  which is just 



The 's cancel in the first term on the bottom,
leaving  which is just 



Finally the second term on the bottom becomes 
which is just  and so we end up with just



Edwin