Answer:
Today, gasoline prices are $3.44 per gallon.
One year ago, gasoline prices were $3.75 per gallon.
Part A
=> The change is: 3.44 - 3.75 = -0.31
=> The percent change is: -0.31/3.75 = -0.083 = -8.3% of last year's price.
Part B
You calculate the change by subtract the current year's price to the last year's price. If the change is negative, it means the price is down. If the change is positive, it means the price is up.
Next, you divide last year's price by the change to get the percent change.
This negative percent change (-P) can be seen as the fact that last year you bought an amount of gallon which cost 100$, this year, you buy the same amount, you have a discount which is equal to P dollar.
Hope this helps!
:)
