List and solve the ratios according to the following conditions: 48 to 12 and 16 to x are equal.
依照下面的条件列出比例，并解比例：48比12和16比x的比值相等．
<gadget id="calculator">48 / 12</gadget>
<output>4</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<result>4</result>