That's the first step. If you weigh A and B and they are equal, that is the simplest of the solutions. The difficult solution is when A is not equal to B.

>I don't know this one either, but does it have something to do with breaking down the balls into 3 groups of 4 balls in each group and then comparing the weights of the each group and going on from there? It seems like mathematically it could be broken down...
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>Tracy
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>>You have 12 billiard balls.
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>>One of them is either lighter or heavier than the others.
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>>You can weigh the billiard balls 3 times on a balance scale.
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>>You need to find out which ball it is and whether it is heaver or lighter.