The canteen bought a batch of skipping ropes at a price of 1.5 yuan each and sold them at a price of 2.5 yuan each. When there are 40 skipping ropes left, not only the full cost is recovered, but also a profit of 50 yuan. How many skipping ropes did the canteen buy in total?
小卖部每根1.5元的价格购进一批跳绳，以每根2.5元的价格售出．当卖到还剩40根时，不仅收回全部成本，还获利50元，小卖部一共购进跳绳多少根？
<gadget id="calculator">1.5 * 40</gadget>
<output>60</output>

<gadget id="calculator">60 + 50</gadget>
<output>110</output>

<gadget id="calculator">2.5 - 1.5</gadget>
<output>1</output>

<gadget id="calculator">110 / 1</gadget>
<output>110</output>

<gadget id="calculator">110 + 40</gadget>
<output>150</output>

<result>150</result>