MARKED PRICE(MP) = 2 × Cost PriceLet Cost Price = X⇒ Marked Price = 2xGain when Marked Price = 2x[(2x – x)/x] × 100 = 100%⇒ for 40 % gain, Marked Price should be⇒ 0.4 = (Marked Price` - x)/x⇒ MP’ = 0.4x + x = 1.4xDiscount % = [(MP – MP`)/MP] × 100 = [(2x – 1.4x)/2x] × 100 = 30%