X: (5/14)=21: (5/8).
X：(5/14)=21：(5/8)．
<gadget id="calculator">5 / 14</gadget>
<output>5/14 = around 0.357143</output>

<gadget id="calculator">8 / 5</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">(5/14) * 21 * (8/5)</gadget>
<output>12</output>

<result>12</result>