The length of a rectangle is 15 decimeters, which is 5 decimeters more than the width, what is the perimeter of the rectangle?
一个长方形的长是15分米，比宽多5分米，这个长方形的周长是多少分米．
<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<gadget id="calculator">10 + 15</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>