Hello there!
A quarter pound burger is usually a quarter of a pound, or 1/4-pound. To find the answer, you can divide 3 1/2 by 1/4 or 3.50/0.25. After dividing, George can make 14 quarter pound burgers. To check your answer, you can multiply 14 w/ 0.25 to get 3 1/2 pounds!
I hope this helps!