From the school gate to the street, there are 18 poles with a distance of 30 meters. How many meters is the length from the school gate to the street?
从学校门口到街口一共有18根电线杆的距离都是30米．求从学校门口到街口长多少米？
<gadget id="calculator">18 - 1</gadget>
<output>17</output>

<gadget id="calculator">30 * 17</gadget>
<output>510</output>

<result>510</result>