The mirror is 90 cm long and 50 cm wide. If you want to put lace around the mirror, how long should you buy?
镜子长90厘米，宽50厘米，要在镜子的四周围上花边，需要买多长的花边？
<gadget id="calculator">90 + 50</gadget>
<output>140</output>

<gadget id="calculator">140 * 2</gadget>
<output>280</output>

<result>280</result>