Labeling the balls with the letters a through o, the
neighborhood sums as A through O, and the row sums as
W through Z (from the top), we can solve using the
equations below (which are easily verified geometrically).
A = 24
B = 43
C = 40
D = 41
E = 60
F = 50
G = 36
H = 62
I = 58
J = 45
K = 25
L = 32
M = 45
N = 44
O = 27
a = A - W
j = 8 (this was given)
g = (W + X + Y) - (E + j)
h = (Y + Z) - (K + N)
i = Y - (g + h + j)
d = (G + N) - (Y + Z)
f = (J + L) - (Y + Z)
e = X - (d + f)
k = (X + Y + Z) - (f + H + O)
o = (X + Y + Z) - (d + I + K)
l = (M + j + o) - (h + N)
n = (g + k + M) - (i + L)
m = (L + N) - (Y + Z)
b = (W + X + Y) - (D + f + i + j)
c = W - b