Eve had 20 pieces of pomelos. After giving her friend some pomelos, Eve is left with 1/4 of the pomelos she originally had. How many pomelos did Eve give away?
Eve is left with 20 x 1/4 = 
<gadget id="calculator">20*1/4</gadget>
<output>5</output>
5 pieces of pomelos.
So she gave away 20 - 5 = 
<gadget id="calculator">20-5</gadget>
<output>15</output>
15 pieces of pomelos to her friend.

<result>15</result>