If there are 36 coins of 2 cents and 5 cents, totaling 99 cents, how many coins of 2 cents are there?
如果2分和5分的硬币共有36枚，共99分，则2分的硬币有多少枚．
<gadget id="calculator">36 * 5</gadget>
<output>180</output>

<gadget id="calculator">180 - 99</gadget>
<output>81</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">81 / 3</gadget>
<output>27</output>

<result>27</result>