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For both problems the strategies needed are first finding out the possibilities of which circles each friend can belong in and then trial and error until it follows all the clues. For example, for the first problem, the third clue says that Ed is Frank's only friend so Frank only has one friend. So he must whether be in circle number 6, or circle number 1 since these circles are only connected to one other circle. This means Franks must be in circle number 5, or circle number 2. In the first clue, it says Alan has three friends Barney, Charlie and Daniel therefore Alan should be in circle 4 or circle 2. So from here the strategy trial and error can be used. Let's say Frank was in circle 1 that would lead Ed into circle 2 and Alan into circle 4 which would mean the friends Charlie, Daniel and Barney and Daniel must be in the leftover circles. In clue 2, it says Barney and Ed are both friends with Charlie. But that is not possible to do with the leftover circles. So let's say Frank was in circle 6, which would lead Ed into circle 5 and Alan was in circle 2. That would mean Daniel, Charlie and Barney would be in the circles 1,3 or 4. In the second clue, it says Barney and Ed are both friends with Charlie so that means Charlie should be in circle 4 while Barney in circle 3 which leaves Daniel in circle one. This all follows the clue so it is the answer.