A rectangle has a length of 15 cm and a width of 12 cm. If it is reduced to a certain ratio, the width of the new rectangle is 3 cm, and what is the length in cm?
一个长方形长15厘米，宽12厘米，按一定比例缩小后，新长方形的宽是3厘米，长是多少厘米．
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">15 / 4</gadget>
<output>15/4 = around 3.75</output>

<result>15/4 = around 3.75</result>