The library bought a batch of new books and distributed them to the first-grade children (2/5), and the remaining 30 books were given to the second graders. How many books are there in total?
图书馆买来一批新书，分给一年级小朋友(2/5)，剩下的30本全部给了二年级，这批新书一共有多少本？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 / (3/5)</gadget>
<output>50</output>

<result>50</result>