Answer:
12
Step-by-step explanation:
The total amount in the tin has to be divisible by 5 and 3, so take numbers that are divisible by 5 and 3 and see if the sum works out. It doesn't work for 15, 30, or 45. If you try it with 60, you get this:
60 rubies in the tin.
Mate gets a third, so 20.
Bosun gets a fifth, so 12.
Pirate gets 28.
Add these three numbers together, 20 + 12 + 28 = 60. That sum works, so the bosun gets 12.
