5: The former item of 12 is increased by 15, to keep the ratio unchanged, what should be the latter item
5：12的前项增加15，要使比值不变，后项应多少
<gadget id="calculator">5 + 15</gadget>
<output>20</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<result>4</result>