I like the chocolate part, while my friend likes the fruit part. Even when two people have different preferences, there is a way to divide the cake so that both feel they received at least half of their own value — the divide and choose algorithm.
The rule is simple. You cut the cake (the cutter), and your friend chooses one of the two pieces first (the chooser). You take the remaining piece.
With this rule, you only need to cut the cake so that the two pieces have equal value to you; you guarantee at least 50%, no matter which piece your friend chooses. Your friend also chooses the piece they prefer, so they guarantee at least 50%. Use the slider below to cut the cake and check it yourself.