For how I was shown to this problem, I would first turn 1/2 into 4/8 just so I can get a better picture of the situation without changing anything just yet. I would then review the question. Since the question says “jack got to eat twice the amount of cake as Jill” I was able to identify that “as” means equal. If the question would of have read “Jack got to eat twice the amount of cake than Jill” it would of have been different. I would say that jack ate 2/8 of the cake, since Jill are the other 2/8.
