Build a road, complete 3.78 kilometers every month, and the task can be completed in 5 months. If an extra 0.42 km is repaired every month, how many months can the task be completed?
修筑一条公路，每个月完成3.78千米，5个月可完成任务．如果每个月多修0.42千米，几个月可以完成任务？
<gadget id="calculator">3.78 + 0.42</gadget>
<output>4.2</output>

<gadget id="calculator">5 / 4.2</gadget>
<output>1.190476</output>

<gadget id="calculator">3.78 * 1.190476</gadget>
<output>4.499999</output>

<result>4.499999</result>