If 27 is added to the latter term of 5:3, how much should be added to the former term to keep the ratio unchanged.
如果5：3的后项加上27，要使比值不变，前项应该加上多少．
<gadget id="calculator">27 + 3</gadget>
<output>30</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">5 * 10</gadget>
<output>50</output>

<gadget id="calculator">50 - 5</gadget>
<output>45</output>

<result>45</result>