With the information provided, you can find the sale price by calculating 33% of the price which is the discount and subtracting that amount from the price:
$55.25*33%=$18.23
$55.25-$18.23=$37.02
According to this, the answer is that the sale price is $37.02.
The slope is the relationship between the cost of the gym and how long you are there for. the y-intercept is how much it costs to go to the gym for no hours ie the start-up cost.