ball a weighs 1 1/2 times as much as ball b. find all combinations of ball a and ball b that will be needed to balance 10 ball b?
First possibility:
10 B = 10 B
After that, we can take advantage that 3B weighs as much as 2A, so you can progressive change every 3B for 2A, for example,
7B+2A = 10B
4B+4A = 10B
there is one more that I will leave you to finish.