Clip the 'Save an extra 25% on your first Subscribe & Save order' coupon found on product page
Add the '33.8oz. Biotene Oral Rinse Mouthwash (Dry Mouth)' to cart (as a one-time purchase option)
Proceed to checkout
During the review your order page, locate the 'Subscribe & Save' option and check mark the 'Save 30% today; Save up to 15% on future auto-deliveries' option
Note, be sure to do it for both product
Final price should be $10.21 after extra coupon savings + Multibuy discount + Subscribe & Save option
shipping is free with Prime or if you spend $25 or more (since it falls under the $25+ required limit)