The elder brother weighs 40 kilograms, which is 4/3 of the younger brother's weight. How many kilograms does the younger brother weigh? (Solution by various methods. For example: direct column division formula, multiplication formula, column equation solution, answer with knowledge of ratio...)
哥哥体重40千克，是弟弟体重的(4/3)，弟弟体重多少千克？(用多种方法解．如：直接列除法算式、乘法算式、列方程解、用比的知识解答…)
<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">40 / (4/3)</gadget>
<output>30</output>

<result>30</result>