Answer:
no, since other things are not held constant, including her income
Step-by-step explanation:
The law of demand states that price has an inverse relationship with quantity demanded of a good. As price increases the demand reduces, and as price decreases quantity demanded increases.
However this is true when all other factors reman constant.
In the given scenario the price of hamburger has fallen but Hilary buys less of it. This looks like a violation of the law of demand, but her income has changed so the law of demand may not hold here.
All factors do not remain constant.
Hilary's behaviour can be explained by the concept income effect. Where an increase in income leads to the consumer buying more of expensive goods than cheaper ones.