Liu Shan is 12 years old and weighs 58 kilograms, which is an overweight child. She joins a health club and loses an average of 0.64 kilograms per week. Four weeks have passed. How many kilograms does she weigh now?
刘杉今年12岁，体重为58千克，属于超重儿童．她加入一个健康俱乐部，平均每个星期体重减轻了0.64千克，四个星期过去了，她现在的体重多少千克？
<gadget id="calculator">0.64 * 4</gadget>
<output>2.56</output>

<gadget id="calculator">58 - 2.56</gadget>
<output>55.44</output>

<result>55.44</result>