The school bought a batch of books and distributed them to Class A and Class B. Class A got 20 books, which happened to be 80% of Class B. How many books are there in this batch?
学校买来一批书分给甲、乙两个班，甲班得20本，正好是乙班的80%，问这批书共有多少本？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">20 / (4/5)</gadget>
<output>25</output>

<gadget id="calculator">25 + 20</gadget>
<output>45</output>

<result>45</result>