Can you solve indices

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%.

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.

Neal buys a board game. he pays for the board game and pays $1.54 in sales tax. the sales tax rate is 5.5%. what is the original price of the board game, before tax