You will need nine cards ~ or counters ~ with the digits 1 to 9 on them.
The task is to lay the cards out in a triangle shape, four to each side, in such a way that the digits on each side of the triangle add up to the same total. Move the cards around until the requirements oif the task are met. It is not easy ~ although there are several correct solutions.
The three sums for the picture below are all different at 32~13~18.
A similar ~ slightly easier ~ task is available .
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