math help!

1/a + 1/b + 1/c = 1/8
1/a = 1/8 - 1/b - 1/c
1/a = (bc - 8b - 8c) / 8bc
a = 8bc / (bc-8b-8c)

Similarly, you can get:
b = 8ac / (ac-8a-8c)
c = 8ab / (ab-8a-8b)

a=16
b=32
c=64