The escalator in the shopping mall is moving from bottom to top at a uniform speed. Brother and sister go upstairs on the escalator. The brother walks 20 steps per minute, and the sister walks 15 steps per minute. As a result, the brother reaches the upper floor in 5 minutes, and the younger sister reaches the stairs in 6 minutes. superior. Q: How many steps of the escalator are visible.
商场的自动扶梯以均匀的速度由下往上行驶着，兄妹两人从扶梯上楼，兄每分钟走20级，妹每分钟走15级，结果兄5分钟到达楼上，妹6分钟到达楼上．问：该自动扶梯有多少级可见扶梯．
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">15 * 6</gadget>
<output>90</output>

<gadget id="calculator">100 - 90</gadget>
<output>10</output>

<gadget id="calculator">6 - 5</gadget>
<output>1</output>

<gadget id="calculator">10 / 1</gadget>
<output>10</output>

<gadget id="calculator">20 + 10</gadget>
<output>30</output>

<gadget id="calculator">30 * 5</gadget>
<output>150</output>

<result>150</result>