A batch of children's books are divided into two classes, A and B, according to 6:8. After the division, it was found that Class B got 30 more books than Class A. How many children's books are in this batch?
一批儿童读物，按6：8分给甲、乙两个班．分完后发现，乙班比甲班多分得30本．这批儿童读物有多少本？
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(4/7) - (3/7)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">30 / (1/7)</gadget>
<output>210</output>

<result>210</result>