Does anyone know how to solve this problem? i am stuck. it is using solving systems of equations

Which equations represents circles that have a diameter of 12 units and a center that lies on the y-axis? check all that apply

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%.

What is the measure of angle tvu shown in the diagram below