Six friends are sitting in a circle facing the centre. Adam is sitting to the immediate left of Betty. Charlie is sitting to the immediate right of Frank. Betty is sitting between Adam and Dan. Eve is sitting between Dan and Frank. Who is sitting to the immediate left of Frank?

Let's place the six friends in a circular arrangement facing inwards (clockwise is left, counter-clockwise is right when viewed from positions, or we can establish relative positions step by step):
1. Adam is sitting to the immediate left of Betty.
Let's place Betty at some position. Since everyone faces the centre, immediate left means going in a clockwise direction. So, Adam is immediately clockwise from Betty.
Positions: [Betty] -> (clockwise) -> [Adam]
2. Betty is sitting between Adam and Dan.
Since Adam is on one side of Betty, Dan must be on the other side of Betty.
Positions: [Dan] -> [Betty] -> [Adam] (moving clockwise)
3. Eve is sitting between Dan and Frank.
Since Dan is already next to Betty on his counter-clockwise side, Eve must be on the other side of Dan (moving clockwise). Then Frank is next to Eve.
Positions: [Frank] -> [Eve] -> [Dan] -> [Betty] -> [Adam] (moving clockwise)
4. Charlie is sitting to the immediate right of Frank.
Immediate right means counter-clockwise direction. Looking at our loop, the only empty slot left between Adam and Frank is filled by Charlie. Let's verify: going counter-clockwise from Frank puts us at Charlie, which matches "Charlie is to the immediate right of Frank."
Full circle in clockwise order: [Charlie] -> [Frank] -> [Eve] -> [Dan] -> [Betty] -> [Adam] -> [Charlie]

Now, we need to find who is sitting to the immediate left of Frank:
Facing the center, the immediate left corresponds to the clockwise direction. The person immediately next to Frank in the clockwise direction is Eve.