There are two kinds of chess pieces, black and white, in the box. The number of black pieces is 3 times more than that of white pieces. Take 10 white pieces and 15 black pieces from the box each time. After taking several times, there are 4 white pieces left in the box, 74 How many sunspots are there in the box?
盒子里有黑、白两种棋子，黑子是白子的3倍多2个，每次从盒子里取走10个白子，15个黑子，取了若干次后，盒子里剩下4个白子，74个黑子，盒子里原有黑子多少个．
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">74 - 12 - 2</gadget>
<output>60</output>

<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<gadget id="calculator">30 - 15</gadget>
<output>15</output>

<gadget id="calculator">60 / 15</gadget>
<output>4</output>

<gadget id="calculator">4 * 15</gadget>
<output>60</output>

<gadget id="calculator">60 + 74</gadget>
<output>134</output>

<result>134</result>