Question

How many quarter pound burgers can george make out of 3 1/2 pounds of ground beef ?

Answer 1

Assuming that there is no wastage of beef. 

Note that 3 1/2 = 7/2 = 14/4 = 14 * 1/4 
This means that we can have 14 sets of quarter pound beef. 

This in turn means that George can make 14 quarter pound burgers.

Answer 2

If you take it down to the unit rate George would be able to make 4 quarter pound burgers for every pound (because a quarter is one fourth) you can display this as 4/1 multiply the top and bottom by 3 and get 12/3 meaning George can make 12 out of 3 pounds and the 1/2 pound would be equivalent to 2 fourths or in this case 2 more quarter pound burgers add it to the 12 and the final answer would be 14.