a+b=29.6, ab=5.6, how much is ab?
a+b=29.6，a-b=5.6，求ab是多少？
<gadget id="calculator">29.6 + 5.6</gadget>
<output>35.2</output>

<gadget id="calculator">35.2 / 2</gadget>
<output>17.6</output>

<gadget id="calculator">29.6 - 17.6</gadget>
<output>12</output>

<gadget id="calculator">17.6 * 12</gadget>
<output>211.2</output>

<result>211.2</result>