Three people, A, B, and C, take an airplane, and the weight of the baggage they bring exceeds the free weight, and additional baggage fees must be paid for the excess. A pays 20 yuan, B pays 40 yuan, and C pays 60 yuan. The luggage of three people weighs 150 kg in total. If one person travels with these luggage, he needs to pay an overweight fee of 240 yuan. I would like to ask: How many kilograms of luggage can each person carry for free?
甲、乙、丙三人乘坐飞机，三人所带行李的重量都超过了免费重量，超出部分必须另付行李费．甲付20元，乙付40元，丙付60元．三人的行李共重150千克，如果是一个人带这些行李出行，就需要支付240元的超重费用．请问：每人可以免费携带多少千克的行李？
<gadget id="calculator">3 + 1 + 1</gadget>
<output>5</output>

<gadget id="calculator">150 / 5</gadget>
<output>30</output>

<result>30</result>