THis question has been asked in the forum before..However, there wasnt a detailed explanation to this question... Would some kind soul please help to solve this ..THanks in advance!

**If Kenny gives 18 marbles to Andrew, he will have thrice as many marbles as Andrew. If Andrew gives 12 marbles to kenny, he will have 1/9 of the number of marbles that kenny has. How many marbles does Kenny have at first?**