What is the difference between 20 minus the product of 2.9 and 5.4?
20减去2.9与5.4的积，差是多少？
<gadget id="calculator">2.9 * 5.4</gadget>
<output>15.66</output>

<gadget id="calculator">20 - 15.66</gadget>
<output>4.34</output>

<result>4.34</result>