A rectangular towel is 35 cm long and 15 cm wide, with lace around it, how many centimeters is the lace long?
一张长方形毛巾长35厘米，宽15厘米，在它的四周围上花边，花边长多少厘米？
<gadget id="calculator">35 + 15</gadget>
<output>50</output>

<gadget id="calculator">50 * 2</gadget>
<output>100</output>

<result>100</result>