The exact area of a circle is 81 pi square inches what are the radius and diameter of the circle

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%.

How do i do this activity, is appreciated

Describe the domain and range of y=2(3)^x-2+5