PSLE Mathematics Paper

I don't remember solving this kind of math problem when I was in grade 6. Probably in high school? I don't quite remember as well.

Anyway, the problem was something like this:

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?

This was the kind of problem solving primary 6 student faced during their Primary School Leaving Examination (PSLE) according to the news... Can my children cope up? Yes, they will... Through God's grace, syempre...