please solve as soon as possible(step by step) (make any assumption if needed).

Mackey Company is considering purchasing a new machine to produce its High-Flight line of shoes. The machine has an economic life of five years and will be depreciated over that time using the straight-line method to a zero salvage value for income tax purposes. The machine will have a $40,000 residual value. The machine costs $625,000 and working capital of $90,000 will be needed at all times to maintain production schedules. At the project's end, the working capital can be completely recovered. Each pair of High-Flight shoes will sell for $55 with a variable cost of $19 per pair. An extra $220,000 of fixed costs per year will be necessary to produce the shoes. The company has a 33% average income tax rate and a marginal income tax rate of 38%. Its after-tax cost of capital is 14% Required: Assuming a constant number of shoes sold each year, what is the minimum number of pairs the company must sell annually to justify embarking on the project