The "Green Leaf" supermarket bought a batch of eggs at the price of 3 eggs for 1 yuan, and sold them at the price of 2 eggs for 1 yuan. After half of the eggs were sold, the price was reduced to 7 eggs for 2 yuan. In the end, there are still 10 eggs left for settlement, and the supermarket has already earned 240 yuan, so how many eggs were purchased in total?
"绿叶"超市以1元钱3个鸡蛋的价格购进一批鸡蛋，先以1元钱2个鸡蛋的价格出售，售出一半后，进行促销活动，价格降为2元钱7个．最后还剩下10个鸡蛋进结算，超市已经赚了240元钱，那么购进的这批鸡蛋共有多少个？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">10 * (2/7)</gadget>
<output>20/7 = around 2.857143</output>

<gadget id="calculator">(20/7) + 240</gadget>
<output>1_700/7 = around 242.857143</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) * (2/7)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/7) - (1/3)</gadget>
<output>-4/21 = around -0.190476</output>

<gadget id="calculator">(1/4) + (-4/21)</gadget>
<output>5/84 = around 0.059524</output>

<gadget id="calculator">(1_700/7) / (5/84)</gadget>
<output>4_080</output>

<result>4_080</result>