Question
Three containers, C, A and B, contained 156 marbles. Valen added some marbles into Container C and the number of marbles in Container C tripled. He took out half of the number of marbles from Container A and added another 39 marbles into Container B. As a result, the ratio of the number of marbles in Container C, Container A and Container B became 12 : 2 : 5. What was the ratio of the number of marbles in Container A to the total number of marbles in Container C and Container B at first? Give the answer in its lowest term.
4 m

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Three containers, C, A and B, contained 156 marbles. Valen added some marbles into Container C and the number of marbles in Container C tripled. He took out half of the number of marbles from Container A and added another 39 marbles into Container B. As a result, the ratio of the number of marbles in Container C, Container A and Container B became 12 : 2 : 5. What was the ratio of the number of marbles in Container A to the total number of marbles in Container C and Container B at first? Give the answer in its lowest term.