There are 40 red and green balls, the number of red balls is (5/8), how many are green balls?
红绿两种球共有40个，红球个数占(5/8)，绿球有多少个．
<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">40 * (5/8)</gadget>
<output>25</output>

<gadget id="calculator">40 - 25</gadget>
<output>15</output>

<result>15</result>