There are two kinds of glass balls, red and white, in a box. The number of red balls is 2 times more than the number of white balls. Take out 7 white balls and 15 red balls from the box each time. If after several times, there are 3 white balls and 53 red balls left in the box. How many red balls are there in the box?
箱子里红、白两种玻璃球，红球数是白球数的3倍多2只，每次从箱子里取出7只白球、15只红球．如果经过若干次以后，箱子里剩下3只白球、53只红球．那么箱子里原有红球多少只？
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">53 - 9 - 2</gadget>
<output>42</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<gadget id="calculator">21 - 15</gadget>
<output>6</output>

<gadget id="calculator">42 / 6</gadget>
<output>7</output>

<gadget id="calculator">15 * 7</gadget>
<output>105</output>

<gadget id="calculator">105 + 53</gadget>
<output>158</output>

<result>158</result>