A plane takes off from Guangzhou and arrives in Urumqi in 4.5 hours at a speed of 720 kilometers per hour. When returning to the headwind, the speed is slower than before (1/6). How many hours will it take to fly the plane back? (Solution of column equation)
一架飞机从广州起飞，以每小时720千米的速度，飞行4.5小时到达乌鲁木齐．返回时逆风，速度比原来减慢了(1/6)．飞机返回时需要飞行多少小时？(列方程解)
<gadget id="calculator">720 * 4.5</gadget>
<output>3_240</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">720 * (1/6)</gadget>
<output>120</output>

<gadget id="calculator">720 - 120</gadget>
<output>600</output>

<gadget id="calculator">3_240 / 600</gadget>
<output>27/5 = around 5.4</output>

<result>27/5 = around 5.4</result>