The length of the blackboard is 5 meters, and the width is 2 meters less than the length. To install steel bars on the edge of the blackboard, how many meters of steel bars are needed?
黑板长5米，宽比长少2米，要给黑板边缘安装钢条，需钢条多少米？
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>