Additional question: Xiaohong used a ribbon to wrap the gift box. Half of the ribbon was used for the first time, and 2.5 decimeters were used for the second time, leaving 7.2 decimeters of the ribbon. How many decimeters is this ribbon long?
附加题：小红用一条彩带包装礼盒，第一次用去了这条彩带的一半，第二次用去的比剩下的一半还多2.5分米，这时彩带还剩下7.2分米．这条彩带一共长多少分米？
<gadget id="calculator">7.2 + 2.5</gadget>
<output>9.7</output>

<gadget id="calculator">9.7 * 2 * 2</gadget>
<output>38.8</output>

<result>38.8</result>