broad river has A. There are two docks in B. It takes 4.5 hours for a ship to go from A to B and 3.5 hours to return. If the speed of the water is 2 kilometers per hour, what is the speed of the ship?
一条宽阔的大河有A．B两个码头，一艘轮船从A去B要用4.5小时，回来用3.5小时，如果水流的速度是每小时2千米，那么轮船的速度是多少？
<gadget id="calculator">2 * 3.5</gadget>
<output>7</output>

<gadget id="calculator">2 * 4.5</gadget>
<output>9</output>

<gadget id="calculator">7 + 9</gadget>
<output>16</output>

<gadget id="calculator">4.5 - 3.5</gadget>
<output>1</output>

<gadget id="calculator">16 / 1</gadget>
<output>16</output>

<result>16</result>