This topic is locked. If you want to discuss this question please re-post it in the respective forum.
What is the best approach here? I tryed the venn diagram, but it did not help.
Each of three charities in East Side has 8 persons serving on its board of directors. If exactly 4 persons serve on 3 boards each and each pair of charities has 5 persons in common on their boards of directors, then how many distinct persons serve on one or more boards of directors?