Xiao Zhang takes the escalator downstairs at the subway station. If he goes down 14 steps, it will take 30 seconds to reach the bottom from the top of the escalator; if he goes down 28 steps, it will take 18 seconds to reach the bottom from the top of the escalator. , how many steps the escalator has.
小张在地铁站乘自动扶梯下楼，如果他向下走14级时，那么需30秒可由自动扶梯顶端到达底部；如果他向下走28级时，那么需18秒可由自动扶梯顶端到达底部，则这部自动扶梯共有多少级．
<gadget id="calculator">28 - 14</gadget>
<output>14</output>

<gadget id="calculator">30 - 18</gadget>
<output>12</output>

<gadget id="calculator">14 / 12</gadget>
<output>7/6 = around 1.166667</output>

<gadget id="calculator">(7/6) * 30</gadget>
<output>35</output>

<gadget id="calculator">35 + 14</gadget>
<output>49</output>

<result>49</result>