The store shipped in a batch of automatic pens, the wholesale price was 5 yuan each, and the selling price was 9 yuan each. So far, there are only 6 pens left. Excluding all costs, the store has made a profit of 90 yuan. How many of these automatic pens did the store ship in total?
商店运进一批自动笔，批发价5元一支，售价9元一支，到目前为止还剩6支，除去所有成本，商店已经赚了90元．商店一共运进多少支这种自动笔？
<gadget id="calculator">6 * 9</gadget>
<output>54</output>

<gadget id="calculator">54 + 90</gadget>
<output>144</output>

<gadget id="calculator">9 - 5</gadget>
<output>4</output>

<gadget id="calculator">144 / 4</gadget>
<output>36</output>

<result>36</result>