An engineering team built an underground railway, originally planned to build 7.2 kilometers per day, and completed it in 15 days. The actual repair is 1.8 kilometers more than the plan every day. How many days can the repair be completed?
某工程队修筑地下铁路，原计划每天修7.2千米，15天修完．实际每天比计划多修1.8千米，实际几天可以修完？
<gadget id="calculator">7.2 * 15</gadget>
<output>108</output>

<gadget id="calculator">7.2 + 1.8</gadget>
<output>9</output>

<gadget id="calculator">108 / 9</gadget>
<output>12</output>

<result>12</result>