Solution: Which Bike Is Free? Math Puzzle

To help figure out this puzzle, we drew a diagram. To keep it simple, we drew the bicycles as circles and the lamppost as a gray dot.

We realized that we didn’t have to chain all the bikes as described in the puzzle and then remove two of the chains. The only important information is which bikes Bart’s chain had locked up. What Omar or Chang did is unnecessary information, since in the end they removed their chains. Since Bart chained his bike to the lamppost and to Chang’s bike, those two bikes remained tied up. Omar’s bike was free.