9) A regional store is trying to determine the profit-maximizing coupon program for the store's laundry detergent brand. Elasticity of demand for coupon users is -3, and the elasticity of demand for non-users of the coupon for the store brand is -1.5. If the full retail (undiscounted) price of the detergent is $10 per box, what is the optimal discount to provide for coupon users? The optimal strategy is to charge the same price to both groups 25% off 75% off O 50% off None of the above