Xiaohua has a 20-meter-long ribbon, which is 2.23 meters long for Xiaojing and 1.77 meters long for Xiaoliang. How many rice ribbons does Xiaohua have left?
小华有一根长20米的彩带，送给小景2.23米，送给小亮1.77米．小华还剩多少米彩带？
<gadget id="calculator">2.23 + 1.77</gadget>
<output>4</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<result>16</result>