Moving 4,000 glass bottles, it is stipulated that the shipping fee is 0.2 yuan for moving one, but 1.3 yuan for breaking one. If the total shipping fee is 780.5 yuan after shipping, how many bottles were broken during the transfer?
搬运4000个玻璃瓶，规定搬一个得运费0.2元，但打碎一个要赔1.3元．如果运完后共得运费780.5元，搬运中打碎几个瓶子？
<gadget id="calculator">4_000 * 0.2</gadget>
<output>800</output>

<gadget id="calculator">800 - 780.5</gadget>
<output>19.5</output>

<gadget id="calculator">1.3 + 0.2</gadget>
<output>1.5</output>

<gadget id="calculator">19.5 / 1.5</gadget>
<output>13</output>

<result>13</result>