Kindergarten bought 84 balls, the small class got 1/3 of these balls, the middle class got 24 balls, what fraction of these balls got the big class?
幼儿园买来84个皮球，小班分得这些球的(1/3)，中班分得24个，大班分得这些皮球的几分之几？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (1/3) - (2/7)</gadget>
<output>8/21 = around 0.380952</output>

<result>8/21 = around 0.380952</result>