Xiao Ming's weight is 28 kg, his father's weight is three times that of Xiao Ming's, and his mother's weight is 25 kg lighter than his father's. How much is his mother's weight?
小明的体重是28千克，爸爸的体重是小明的3倍，妈妈的体重比爸爸轻25千克，妈妈的体重是多少千克？
<gadget id="calculator">28 * 3</gadget>
<output>84</output>

<gadget id="calculator">84 - 25</gadget>
<output>59</output>

<result>59</result>