bookstore sells a kind of wall calendar. It can get a profit of 18 yuan for each copy sold. After a part is sold, each copy is sold at a reduced price of 10 yuan. All of them are sold out. It is known that the number of calendars sold at the reduced price is the original price (2/ 3) The bookstore made a total profit of 2870 yuan after selling out this kind of calendar. How many copies of this kind of calendar were sold by the bookstore?
某书店出售一种挂历，每售出1本可获得18元利润，售出一部分后每本减价10元出售，全部售完，已知减价出售的挂历本数是原价出售挂历的(2/3)，书店售完这种挂历共获利润2870元，书店共售出这种挂历多少本？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) * 18</gadget>
<output>12</output>

<gadget id="calculator">(2/3) * 10</gadget>
<output>20/3 = around 6.666667</output>

<gadget id="calculator">12 - (20/3)</gadget>
<output>16/3 = around 5.333333</output>

<gadget id="calculator">18 + (16/3)</gadget>
<output>70/3 = around 23.333333</output>

<gadget id="calculator">2_870 / (70/3)</gadget>
<output>123</output>

<gadget id="calculator">123 * (2/3)</gadget>
<output>82</output>

<gadget id="calculator">123 + 82</gadget>
<output>205</output>

<result>205</result>