From A to B, Wang Dong ran 6 meters per second for the first half of the time, and 4 meters per second for the second half of the time. It is known that A and B are 300 meters apart, how many seconds did he run in the second half of the distance?
王东从A地到B地，前一半时间每秒跑6米，后一半时间每秒跑4米．已知A，B两地相距300米，那么他后一半路程跑了多少秒？
<gadget id="calculator">300 / 2</gadget>
<output>150</output>

<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">300 / 5</gadget>
<output>60</output>

<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">150 - 120</gadget>
<output>30</output>

<gadget id="calculator">30 / 6</gadget>
<output>5</output>

<gadget id="calculator">5 + 30</gadget>
<output>35</output>

<result>35</result>