There are 60 red and yellow balls in a box, if 2 out of every 5 balls are yellow, how many red balls are there in the box?
一个盒子里有红、黄两种球共60个，已如每5个球中有2个是黄球，盒子里红球有多少个．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">60 * (3/5)</gadget>
<output>36</output>

<result>36</result>