Question

There was 2/3 of a pan of lasagna in the refrigerator. Bill and his friends ate 1/2 of what was left. How much of the pan did they eat?

Answer 1

If 2/3 of the lasagna is in the refrigerator, 1/3 of it is left.  If Bill and his friends eat 1/2 of the 1/3 remaining, they eat a total of 1/2*1/3=1/6 of the full pan of lasagna.