Assume that the marginal cost to grocery of selling a bottle of salad dressing to customers who use coupons versus those who don't is identical and equal to $1.50. If the elasticity of demand for coupon users is 5 versus 1.25 for non-coupon users, how much per unit discount should the store make available through coupons? What if the coupon users have a demand elasticity of 2 versus 1.25 for non-coupon users?