(4/5) of a number is 28, what is its (2/7).
一个数的(4/5)是28，它的(2/7)是多少．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">28 / (4/5)</gadget>
<output>35</output>

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

<gadget id="calculator">35 * (2/7)</gadget>
<output>10</output>

<result>10</result>