# 3 guys play frisbee [closed]

Story:

Three guys A, B and C meet daily to play frisbee. They determined: Always if A doesn't have a frisbee, then B has one. If B doesn't take along a frisbee, then C has one.

Today B hasn't a frisbee.

Question:

Which boys have a frisbee today?

• Well, without even thinking, 'boys' is plural and B doesn't have a frisbee so A and C do. – Duck Jun 21 '19 at 18:49
• How is this a puzzle? It’s a direct statement of a textbook style problem with an entirely mechanical solution. We generally don’t allow those. See Are math-textbook-style problems on topic? for more info. – Rubio Jun 21 '19 at 20:16
• I'm voting to close this question as off-topic because this is not a puzzle, nor is it related to puzzle-solving. – Brandon_J Jun 21 '19 at 21:08

Solution:

A and C have frisbees

Because:

If A would't has a frisbee then B would has one. And when B has no frisbee, then C has one

A and C have frisbees.

This follows from the 2nd statement and the contrapositive of the 1st statement. Specifically:

1. "if A doesn't have a frisbee, then B has one." Therefore, if B doesn't have a frisbee, then A does.

2. "If B doesn't take along a frisbee, then C has one." Therefore, since B doesn't have one, C also does.