Lets divide the problem in parts, first for sandwiches she used 3/4 out of 20 ounces of ham: (3/4)(20) = 60/4 = 15 so for sandwiches Lauren used 15 ounces Then for omelete she used 1/5, that is: (1/5)(20) = 20/5 = 4 then Lauren used 4 ounces for omelete So Lauren used 15 ounces for sandwiches and 4 ounces for omelete, that is 19 ounces in total, so there are left from the 20 original ounces: 20 - 19 = 1 there is 1 ounce of ham left