GUYS PLEASE ANSWER THIS QUESTION IM DESPERATE

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%.

Can any one me with the answers to these questions asap?

What does the sign of the slope tell you about a line?