Expanding the equation:

(x + b) + (x + 2b) - (x - 3b) = 8b

x + b + x + 2b - x + 3b = 8b

Combine like terms:

2x + 6b = 8b

Subtract 6b from both sides:

2x = 2b

Divide by 2:

x = b

Therefore, the equation simplifies to b = 8b.