Put red flags on one side of the sports field, every 5 meters. A total of 13 sides are inserted from one end to the other. How long is one side of the playground?
在运动场的一边插红旗，每隔5米插一面．从一端到另一端一共插了13面，运动场的一边有多长．
<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<gadget id="calculator">5 * 12</gadget>
<output>60</output>

<result>60</result>