Two identical cruise ships set off from Port A in opposite directions at the same time, with a speed of 20 kilometers per hour and a water speed of 4 kilometers per hour. After 4 hours, the two cruise ships returned to Port A at the same time. Then during these 4 hours, how many hours are the two ships moving in the same direction?
两艘同样的游轮从A港同时向相反方向开出，船速是每小时20千米，水速是每小时4千米，4小时后两艘游轮同时回到了A港．那么在这4小时时间里，有多少小时两艘船的前进方向是一样的．
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">4 * (3/5)</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 * (2/5)</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">(12/5) - (8/5)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>