Help pls 15 ponits math

Adepartment store purchases screen-printed t-shirts at a cost of $5 per shirt. they mark up the price 150% (making the selling price 250% of the store's purchase price) and put them on the sales floor. every month that a t-shirt doesn't sell, the store reduces the selling price by 25%.

100 points, hi, i’m not sure how to get the equation from the graph and table.

There are 45 questions on your math exam. you answered 810 of them correctly. how many questions did you answer correctly?