During the flood season of a certain river, the water speed in the middle stream is quite different from that along the coast, 45 miles per hour in the middle stream, and 25 miles per hour along the coast. Today there is a steamboat going down the middle stream, traveling 440 miles in 4 hours, how many hours does it take to return from the coast to the original place?
某江汛期时中流与沿岸的水速有很大不同，中流每小时45里，沿岸每小时25里．今有一汽船顺中流而下，4小时行驶了440里，问从沿岸返回原处需几小时？
<gadget id="calculator">440 / 4</gadget>
<output>110</output>

<gadget id="calculator">110 - 45</gadget>
<output>65</output>

<gadget id="calculator">65 - 25</gadget>
<output>40</output>

<gadget id="calculator">440 / 40</gadget>
<output>11</output>

<result>11</result>