Since the dress is "Marked save 25%" this means yuo pay 75% of the $50 price. Remember, 100-25 = 75. This means you pay 0.75*50 = $37.50 and yuo got a discount of $12.50.
<span>Inscribed angles on a diameter are right angles; the radius of a circle is perpendicular to the tangent where the radius intersects the circle.</span>