The four sides of a quadrilateral are 11 meters, 15 meters, 18 meters, and 9 meters respectively, so what is the perimeter of the quadrilateral in meters?
一个四边形的四条边分别是11米、15米、18米、9米，那么这个四边形的周长是多少米．
<gadget id="calculator">11 + 15 + 18 + 9</gadget>
<output>53</output>

<result>53</result>