If a square with a side length of 15 cm is reduced to a ratio of 1:3, what is the side length of the square?
把一个边长15厘米的正方形按1：3的比缩小后，正方形的边长是多少．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">15 * (1/3)</gadget>
<output>5</output>

<result>5</result>