Clothing Store in Dallas - Math riddle


There is a clothing store in Dallas. The owner has made his own method of pricing items. A vest costs $20, socks cost $25, a tie costs $15, and a blouse costs $30. Using the method,

How much would a pair of underwear cost?

 

Explanation :  

Underwear would cost 45 dollars, since there are 9 letters in "Underwear.“

The cost of each item is solved by taking the number of letters in the item and multiplying it by 5.
Example,

V E S T = 4 letters * 5 = 20
S O C K S = 5 letter * 5 = 25
T I E = 3 letters * 5 = 15 

So, 
U N D E R W E A R = 9 letters * 5 = 45