4/12 = y/9 what is the proportional relationship

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%.

Which of the following is correct interpretation of the expression -4+13

Im literally having a mental breakdown