The school bought 42 packs of exercise books, 20 books in each pack. Each class is divided into 56 books. How many classes can these exercise books be divided into?
学校买来42包练习本，每包20本．每班分56本，这些练习本能够分给几个班？
<gadget id="calculator">20 / 56</gadget>
<output>5/14 = around 0.357143</output>

<gadget id="calculator">42 * (5/14)</gadget>
<output>15</output>

<result>15</result>