A bookstore bought a batch of books at a price of 14.98 yuan each, and each book was sold at 21.7 yuan. After selling out, in addition to recovering the cost, it also obtained a profit of 504 yuan. How many books did this bookstore buy in total?
某书店经每本14.98元的价格购进一批书，每本售价21.7元，卖完后，除了收回成本外，还获得了504元的利润，这个书店共购进这批书多少本？
<gadget id="calculator">21.7 - 14.98</gadget>
<output>6.72</output>

<gadget id="calculator">504 / 6.72</gadget>
<output>75</output>

<result>75</result>