Add 15 to the former term of 30:17, how much should the latter term be multiplied to keep the ratio constant
把30：17的前项增加15，要使比值不变，后项应该乘多少
<gadget id="calculator">30 + 15</gadget>
<output>45</output>

<gadget id="calculator">45 / 30</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>