This is for an exam and I need help…

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%.

Question 5 spring semester final exam math evaluate

Can someone check if i did this correct. it’s number 4 if you’re wondering.