The fruit shop bought 20 boxes of apples and pears and paid 465 yuan. It is known that apples are 25 yuan per box, and Sydney is 20 yuan per box. So how many boxes of apples does the fruit shop buy?
水果店购进苹果和雪梨共20箱，付出465元．已知苹果每箱25元，雪梨每箱20元．那么水果店购进苹果多少箱．
<gadget id="calculator">25 * 20</gadget>
<output>500</output>

<gadget id="calculator">500 - 465</gadget>
<output>35</output>

<gadget id="calculator">25 - 20</gadget>
<output>5</output>

<gadget id="calculator">35 / 5</gadget>
<output>7</output>

<gadget id="calculator">20 - 7</gadget>
<output>13</output>

<result>13</result>