Xiaojun has 28 glass balls, and Xiaoli has fewer glass balls than Xiaojun (2/7). How many fewer glass balls does Xiaoli have than Xiaojun?
小军有28颗玻璃球，小力的玻璃球比小军少(2/7)．小力的玻璃球比小军少多少颗？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">28 * (5/7)</gadget>
<output>20</output>

<gadget id="calculator">28 - 20</gadget>
<output>8</output>

<result>8</result>