There are two naughty children walking against the direction of the escalator. The escalator has 150 steps. The boy can walk 3 steps per second, and the girl can walk 2 steps per second. As a result, the girl walks 300 seconds from one end of the escalator to the other. How many seconds does the boy walk?
有两个頑皮的小孩子逆着自動扶梯行駛的方向行走．该扶梯共有150级台阶，男孩每秒可以走3级台阶，女孩每秒可以走2级台阶，结果从扶梯的一端到达另一端，女孩走了300秒，那么男孩走了多少秒．
<gadget id="calculator">150 / 300</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 - (1/2)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">3 - (3/2)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">150 / (3/2)</gadget>
<output>100</output>

<result>100</result>