请问边际效用，价格，和数量的关系

最好能告诉我下面的题怎么解

each week,Tom wu buys two hamburget at $2 each,eight cokes at $0.5 each,and eight slices of pizza at $1 each,but he buys no hot dogs at$1.5 each.what can you deduce about Tom's marginal utility for each of the four goods?

我是一本科新生,对经济学还处于迷茫状态,请帮忙啊,谢谢~~~