The Cannonballs riddle
A ship sailor has stacked cannonballs in two tetrahedral pyramids. In order to impress the ship captain he decided to combine the cannonballs in both of the pyramids and create one large pyramid. The smallest number of cannonballs he can have if the two pyramids are the same size is twenty ( we assume that he uses every cannonball in both pyramids).You can see that solution in the picture below.
However if the two smaller pyramids are different sizes what would be the minimum number of cannonballs he could use to make one larger tetrahedral pyramid?
