A rectangular vegetable field is 10 meters long, and its width is 5 meters less than its length. What is the perimeter of this vegetable field in meters?
一个长方形的菜地长10米，宽比长少5米，这块菜地的周长是多少米？
<gadget id="calculator">10 - 5</gadget>
<output>5</output>

<gadget id="calculator">10 + 5</gadget>
<output>15</output>

<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<result>30</result>