The escalator in the shopping mall runs from top to bottom at a constant speed. The two children think the escalator is too slow, so on the moving escalator, the boy goes down 2 steps per second, and the girl goes down 3 steps every 2 seconds. It takes 40 seconds to reach the downstairs, and the girl takes 50 seconds to reach the downstairs. When the escalator is stationary, how many steps can the escalator see?
商场的自动扶梯匀速由上往下行驶，两个孩子嫌扶梯走得太慢，于是在行驶的扶梯上，男孩每秒向下走2级，女孩每2秒向下走3级，结果男孩用40秒钟到达楼下，女孩用了50秒钟到达楼下，问当该扶梯静止时，扶梯可看到的梯级共有多少级？
<gadget id="calculator">40 * 2</gadget>
<output>80</output>

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

<gadget id="calculator">50 * (3/2)</gadget>
<output>75</output>

<gadget id="calculator">80 - 75</gadget>
<output>5</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 + (1/2)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) * 40</gadget>
<output>100</output>

<result>100</result>