Xiao Ming's weight is 42 kg, which is half of his father's weight, and his father's weight is three times that of his younger brother. How many kilograms does your brother weigh?
小明的体重是42千克，是爸爸体重的一半，而爸爸的体重是弟弟的3倍．弟弟的体重是多少千克？
<gadget id="calculator">84 / 3</gadget>
<output>28</output>

<result>28</result>