I believe that 55/80 is not in it's simplest form because 5 can divide the two numbers. When a number is in it's simplest form, it means that no other number can divide the two numbers and it is in it's lowest form. Any way, when 5 divides 55, you get 11, and when 5 divides 80, you get 16. So the answer should be;
11/16. Hope i helped. Have a nice day.
