Let B's capital be \(x\) rupees.
∴ If A's profit is 600 rupees, then B's profit = (1400 - 600) rupees = 800 rupees.
According to the condition, \(6000:x=600:800\)
or, \(\cfrac{6000}{x}=\cfrac{600}{800}\)
or, \(600x=6000×800\)
or, \(x=\cfrac{6000×800}{600}=8000\)
∴ B's capital is 8000 rupees (Answer).