The sum of two adjacent odd numbers is 20, what is the product of these two odd numbers?
两个相邻奇数的和是20，这两个奇数的乘积是多少．
<gadget id="calculator">20 - 2</gadget>
<output>18</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 + 2</gadget>
<output>11</output>

<gadget id="calculator">11 * 9</gadget>
<output>99</output>

<result>99</result>