In these numeric logic puzzles, you fill in blanks so that the sum of each box is made by adding the numbers in the adjoining half-height boxes. Note that some of these numbers are negative, and may produce negative sums. Eventually you reach the center, in which the final sum is zero, representing a kind of equilibrium — you have achieved your quest for balance.
Whit has kindly provided two sets of printable puzzles, small and large, which contain more detailed instructions, a fistful of puzzles, and their answers. Here are the two sample sets: