Answer:
The formula which is applied is spending her own money and it is on someone else.
Explanation:
The formula of the economist named Milton Friedman buyer value, involves spending her own money on herself, spending her own money on someone else, spending someone else's money on herself and spending someone else's money on someone else.
In the given situation, the person is buying a gift which is to be presented to her niece. So, she is buying the gift for someone else and the money which is spend on the gift is her own money.
