school buys two kinds of books, A and B, in a bookstore. The number of books of type B is 3/5 of the number of books of type A. The number is twice the amount paid for buying a book of type B. It is known that each book of type B is 15 yuan, so how much is the price of each book of type A?
某学校到书店购买甲、乙两种书，买乙种书的册数是甲种书册数的(3/5)，如果买甲种书按九折优惠，则买甲种书所付的钱数是买乙种书所付钱数的2倍．已知乙种书每本15元，那么甲种书每本定价多少元？
<result>20</result>