Help with a) and b)

GlaxoSmithKline plc is a pharmaceutical company. It is considering the replacement of one of its existing machines with a new model. The existing machine can be sold now for 8,000. The new machine costs 50,000 and will generate free cash flows of 11,416.55 pa. over the next 6 years. The corporate tax rate is 35%. The new machine has average risk. GlaxoSmithKline's debt-equity ratio is 0.5 and it plans to cost of equity is 13.10% a) Compute GlaxoSmithKline's weighted average cost of capital. b) What is the NPV of the new machine and should GlaxoSmithKline replace the old machine with the new one