A road in the school is 36 meters long. How many colored flags are needed to plant a colored flag every four meters on both sides of the road?
学校的一条路长36米，在路的两边每隔四米插一面彩旗一共需要多少面彩旗﹖
<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>