There are 7 bags of rice, their weights are 12, 15, 17, 20, 22, 24, 26 kg respectively. A takes one bag first, and B, C, and D take the rest. It is known that B and C take exactly the same amount of weight, and both of them are twice the weight taken by D. So how many kilograms is the weight of the bag that A took away first?
有7袋米，它们的重量分别是12、15、17、20、22、24、26公斤．甲先取走一袋，剩下的由乙、丙、丁取走．已知乙和丙取走的重量恰好一样多，而且都是丁取走重量的2倍．那么甲先取走的那一袋的重量是多少公斤？
<result>26</result>