A, B, and C take a train at the same time with a total of 150 kilograms of luggage. A pays 8 yuan for the luggage, B pays 7 yuan, and C pays 9 yuan. How many kilograms is the free luggage per person?
甲乙丙三人同时乘火车共带行李150千克，行李甲付8元，乙付7元，丙付9元，如果甲的行李分给乙丙二人带，则乙丙都要付18元．则每人的免费行李是多少千克．
<gadget id="calculator">18 + 18</gadget>
<output>36</output>

<gadget id="calculator">36 * 150</gadget>
<output>5_400</output>

<gadget id="calculator">8 + 7 + 9</gadget>
<output>24</output>

<gadget id="calculator">24 * 150</gadget>
<output>3_600</output>

<gadget id="calculator">5_400 - 3_600</gadget>
<output>1_800</output>

<gadget id="calculator">36 * 3</gadget>
<output>108</output>

<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<gadget id="calculator">108 - 48</gadget>
<output>60</output>

<gadget id="calculator">1_800 / 60</gadget>
<output>30</output>

<result>30</result>