7, 9, 28 and how much can form a proportion.
7、9、28和多少，可以组成比例．
<gadget id="calculator">9 / 7</gadget>
<output>9/7 = around 1.285714</output>

<gadget id="calculator">28 * (9/7)</gadget>
<output>36</output>

<result>36</result>