Yesterday came across a news report saying that this year math PSLE paper was again tough and they have given an example of one of the question AND suprisingly i myself also don't know how to solve...how embarrasing i spend quite some time trying to solve but to no avail anyone knows

Here is the Question:

"Jim bought some chocolates and gave half of it to Ken. Ken bought some sweets and gave half of it to Jim. Jim ate 12 sweets and Ken ate 18 chocolates. The ratio of Jim’s sweets to chocolates became 1:7 and the ratio of Ken’s sweets to chocolates became 1:4. How many sweets did Ken buy?"


Ans:68