The weight W kg of a metal bar varies jointly as its length L meters and the square of its diameter d meters. If w = 140 when d = 42/3 and L = 54, find d in terms of W and L.
A. \(\sqrt{\frac{42W}{5L}}\) B. \(\sqrt{\frac{6L}{42W}}\) C. \(\frac{42W}{5L}\) D. \(\frac{5L}{42W}\)
