Hello, so let's break this down.
There is a total of 109,000 votes all together.
If you want to find out how much candidate B received, all you need to do is subtract 15,000 from 109,000 which would be 94,000.
If you want to make sure that is correct, add candidate B's total votes from candidate C's total votes if it adds up to 209,000 (94,000+15,000 = 209,000).
Hope this helps! =)