#21 Expensive Underwear?

There is a clothing store in Bartlesville, where the owner of this store has devised his own pricing method. a vest costs $20, socks cost $25 dollars, a tie costs $15 dollars, a blouse costs $30 dollars. using his method, how much would a pair of underwear cost?

#20 Think Tropical

a little pool with two layers of wall around it. one is white and soft, the other, dark and hard. amidst a light brown grassy lawn, with an outline of green grass around it
What am I?

this riddle is way too vague, because I didn't get it until I saw this hint, but I thought it was kind of clever, so I have put this said hint into the post title (Think Tropical)

Happy Riddling!