A picture frame is 30 decimeters long and 20 decimeters wide, and it is surrounded by lace, how many meters of lace is needed?
一个镜框长30分米，宽20分米，在它的四周用花边围起来，需要花边多少米．
<gadget id="calculator">30 + 20</gadget>
<output>50</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">50 * (1/5)</gadget>
<output>10</output>

<result>10</result>