The latter term of 12:5 is increased to 15, if the size of the ratio remains unchanged, how many times should the former term be enlarged
12：5的后项增加到15，要是比值的大小不变，前项应扩大到原来的多少倍
<gadget id="calculator">15 / 5</gadget>
<output>3</output>

<result>3</result>