Allison wants to buy a skirt that has a regular price of $30.
 • The skirt is on sale for 1/5 off the regular price.
 Allison has a coupon that will take 1/10 off the sale price.
 • There is no sales tax on clothing.
 If Allison pays with a $50 bill, how much change will she receive?
 (Note: Express the answer as dollars.cents.)