It takes 16 hours for a ship to sail 120 kilometers downstream and 80 kilometers upstream; it also takes 16 hours to sail 60 kilometers downstream and 120 kilometers upstream. Find the velocity of the water flow.
一艘轮船顺流航行120千米，逆流航行80千米共用16时；顺流航行60千米，逆流航行120千米也用16时．求水流的速度．
<gadget id="calculator">120 / 80</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">80 * (3/2)</gadget>
<output>120</output>

<gadget id="calculator">120 + 120</gadget>
<output>240</output>

<gadget id="calculator">240 / 16</gadget>
<output>15</output>

<gadget id="calculator">15 / (3/2)</gadget>
<output>10</output>

<gadget id="calculator">15 - 10</gadget>
<output>5</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>