$(6$ points$)$ In town, store A sells Air Garnett's for $$100$ and Ronko Coffee Grinder for $$125.$ Store B$,$ which is $20$ miles away, sells the same products for $$75$ and $$100$ respectively.

a$.(2$ points$)$ What is the expense $($in conceptual terms$)$ of Joe Blow going to store $B?$

b$.(2$ points$)$ What is the opportunity cost $($in conceptual terms$)$ of Joe Blow going to store $B?$

c$.(2$ points$)$ On Saturday, Joe Blow drives his $18$ year old daughter to Store B to get a pair of Air Garnets in order to save $$25.$ Two weeks later, Joe Blow refuses to drive his wife to Store B to buy a Ronko Coffee Grinder in order to save $$25.$ Assuming Joe Blow is acting in his perceived best interests, and all other things equal $($like the price of gas, weather, etc...$),$ so that the only difference is who is going to the store and what they will buy, explain Joe Blow's behavior using the rational rule.