We want to find the better option between these two:
1. A 55 inch LCD TV for $920.
2. A 42 inch LCD TV for $449.
For doing so, we will find the value per inch for each one of the options, and this will be done by making the quotient between the values and the respective inches of every option.
Option 1:

Option 2:

This means that the first option costs approximately 17 dollars per inch, and the second option costs 11 dollars per inch, which means that the second option is cheaper.