Suppose that a museum of modern art discovers the following: adults are willing to pay $20 per ticket to see a Monet exhibit. Students are willing to pay less; 60% of students have WTP of $15, and 40% are willing to pay up to $10. There are no marginal costs to allowing more viewers into the museum. The museum manager decides to set the regular price at $20, and offer a student discount. What discount should it offer?