The ratio of A and B is 5:9, if A=30, then B=how much.
A、B两数的比是5：9，如果A=30，那么，B=多少．
<gadget id="calculator">5 + 9</gadget>
<output>14</output>

<gadget id="calculator">5 / 14</gadget>
<output>5/14 = around 0.357143</output>

<gadget id="calculator">30 / (5/14)</gadget>
<output>84</output>

<gadget id="calculator">84 - 30</gadget>
<output>54</output>

<result>54</result>