There are three kinds of books on the bookshelf, there are 10 books, 5 books, and 5 books respectively. If two types of books are taken out from them, how many ways are there?
书架上有三种书，分别有10本，5本，5本，若从中取出两种类型的书，有多少种取法？
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">2 * 1</gadget>
<output>2</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<result>3</result>