11 different biology books and 8 different chemistry books lie on a shelf. in how many ways can a student pick 2 books of each type?	Pick:
A) 80	B) 160	C) 720	D) 1100	E) 1540
<gadget id="calculator">factorial(11)</gadget>
<output>39_916_800</output>

<gadget id="calculator">11 - 2</gadget>
<output>9</output>

<gadget id="calculator">factorial(9)</gadget>
<output>362_880</output>

<gadget id="calculator">39_916_800 / 362_880</gadget>
<output>110</output>

<gadget id="calculator">110 / 2</gadget>
<output>55</output>

<gadget id="calculator">factorial(8)</gadget>
<output>40_320</output>

<gadget id="calculator">8 - 2</gadget>
<output>6</output>

<gadget id="calculator">factorial(6)</gadget>
<output>720</output>

<gadget id="calculator">40_320 / 720</gadget>
<output>56</output>

<gadget id="calculator">56 / 2</gadget>
<output>28</output>

<gadget id="calculator">55 * 28</gadget>
<output>1_540</output>

<result>E</result>
11 different biology books and 8 different chemistry books lie on a shelf. in how many ways can a student pick 2 books of each type?
multiply(divide(divide(factorial(11), factorial(subtract(11, 2))), 2), divide(divide(factorial(8), factorial(subtract(8, 2))), 2))
"no . of ways of picking 2 biology books ( from 11 books ) = 11 c 2 = ( 11 * 10 ) / 2 = 55 no . of ways of picking 2 chemistry books ( from 8 books ) = 8 c 2 = ( 8 * 7 ) / 2 = 28 total ways of picking 2 books of each type = 55 * 28 = 1540 ( option e )"