Xiao Ming ran a circle on a 360-meter-long circular track. It is known that he ran 4 meters per second for the first half of the distance, and 5 meters per second for the second half of the distance. How many seconds did he take for the second half of the distance?
小明在360米长的环形跑道上跑了一圈，已知他前一半路程每秒跑4米，后一半路程每秒跑5米，则他后一半路程用了多少秒．
<gadget id="calculator">360 / 2</gadget>
<output>180</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">360 / 9</gadget>
<output>40</output>

<gadget id="calculator">40 * 4</gadget>
<output>160</output>

<gadget id="calculator">180 - 160</gadget>
<output>20</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 + 40</gadget>
<output>45</output>

<result>45</result>