The stationery store has a total of 850 fountain pens and ballpoint pens. When the two types of pens are sold in the same number, there are still 123 fountain pens and 87 ballpoint pens left. How many fountain pens does the stationery store have?
文具店有钢笔和圆珠笔共850支，当两种笔卖出同样多的支数时，还剩下钢笔123支，圆珠笔87支，原来文具店有钢笔多少支？
<gadget id="calculator">123 * 2</gadget>
<output>246</output>

<gadget id="calculator">246 - 123 - 87</gadget>
<output>36</output>

<gadget id="calculator">850 + 36</gadget>
<output>886</output>

<gadget id="calculator">886 / 2</gadget>
<output>443</output>

<result>443</result>