please help. what is crossover rate?

Consider the following projects, X and Y where the firm can only choose one. Project X costs S600 and has cash flows of $400 in each of the next 2 years. Project Y also costs $600, and generates cash flows of $500 and $275 for the next 2 years, respectively. Sketch a net present value profile for each of these projects. Which project should the firm choose if the cost of capital is 10 percent? What if the cost of capital is 25 percent? Show all work in the designated spreadsheet. Choice at 109 Project X Choice at 25% | Neither project Rate Crossover Rate