A rectangular mirror is 50 centimeters long and 30 centimeters wide. It is necessary to inlay a metal frame around it. How many centimeters is the frame long?
一个长方形镜子，长是50厘米，宽是30厘米，要在它的四周镶上金属边框，边框长多少厘米？
<gadget id="calculator">50 + 30</gadget>
<output>80</output>

<gadget id="calculator">80 * 2</gadget>
<output>160</output>

<result>160</result>