The store bought a batch of slippers at a price of 6.5 yuan per pair, and the price was 7.4 yuan. When there were 5 pairs left, the profit was 44 yuan. How many pairs are there in this batch of slippers?
商店以每双6.5元的价格购进一批拖鞋，售价为7.4元．卖到还剩5双时，已获利44元．这批拖鞋共有多少双．
<gadget id="calculator">7.4 * 5</gadget>
<output>37</output>

<gadget id="calculator">44 + 37</gadget>
<output>81</output>

<gadget id="calculator">7.4 - 6.5</gadget>
<output>0.9</output>

<gadget id="calculator">81 / 0.9</gadget>
<output>90</output>

<result>90</result>